Photo: Imagn Images

It would be easy to label Greg Jennings as a receiver who has lost his way after leaving the best quarterback in the NFL, Aaron Rodgers. Jennings signed a five-year, $45 million contract with the Minnesota Vikings last year after playing for seven years in Green Bay with the Packers. At his peak, Jennings was never one of the most productive receivers in the league, but he was always very consistent whether he was catching passes from Brett Favre or Rodgers.

In fact, there was a time when a narrative existed that suggested Jennings' production was hindered by playing on such a talented offense. When he left Green Bay for Minnesota, nobody would make that claim.

Before missing half of the 2012 season through injury, Jennings averaged 69 receptions for 1,108 yards and nine touchdowns from 2007 to 2011. During that time he averaged 14.8 games per season, roughly the same number he played during his first year with the Vikings. However, with the Vikings the 29-year-old Jennings had just 68 receptions for 804 yards and four touchdowns. Because he was now playing away from Aaron Rodgers and he was entering the latter stages of his career, it was easy to suggest that Jennings' play was the primary reason for his poor output.

However, that wasn't the case.

The above chart includes plays that were negated by penalty, so that is why Jennings has one more reception than his official total. Target numbers are always unreliable because there is no clear definition, but these target numbers were defined as throws that didn't require the receiver to make a spectacular catch. For example, a one handed fingertip grab didn't count as a catchable target.

Jennings saw a lot of targets last season, but playing with Christian Ponder, Josh Freeman and Matt Cassel made a large chunk of them worthless.

Ponder entered the season as the team's starter, but his combination of poor arm strength and erratic ball placement made it very difficult for Jennings to be consistently productive. The relatively young quarterback repeatedly forced Jennings to make difficult adjustments on the ball when he was open or completely missed him, while he was completely unable to fit the ball into tight windows when Jenning wasn't wide open.

In games where Ponder started and played the full game, Jennings averaged four catchable targets per game. 

The above chart shows every single one of Jennings' catchable targets from Ponder. Ponder started and finished seven games with Jennings and played one more when he was benched for Cassel.  As the chart shows, every single one of Jennings' drops last season came on throws from Ponder and none of his touchdowns came from him. These numbers account for 7.5 games of a 16 game season, so they project out to 64 catchable targets, 53 receptions, 595 yards, zero touchdowns and 11 drops over a full regular season.

In comparison to Cassel, these numbers are startlingly low.

The above chart shows every single one of Jennings' catchable targets from Cassel. Cassel accounted for all of Jennings' targets in six full games and took over from Ponder for half a game when throwing to Jennings. During those games, Ponder averaged four catchable targets per game for Jennings, while Cassel averaged six. More importantly, Cassel's numbers from last season project to 99 catchable targets, 99 receptions, 1,199 yards and 10 touchdowns with zero drops.

Now these numbers could simply be coincidental. Jennings may have had better matchups when Cassel played or he may not have been getting open as often when Ponder was on the field. That's not what the tape suggests though.

One of the strongest attributes that Jennings can boast is his ball skills. Jennings tracks the football in the air and reacts to it as well as anyone in the NFL. He is not a big receiver, but he has a catch radius that allows him to consistently trap the ball with his hands away from his body. While this is an aspect of his game that is very impressive, it's not an aspect of his game that you ideally want to be putting on show on a regular basis. If Jennings is making these kinds of receptions, it's generally because the pass comes in off target.

With Ponder, these kinds of plays were regular.

On this throw, Ponder actually makes a smart decision to keep the bal low and not lead Jennings further infield because there is an incoming safety. However, Ponder pushes the ball too far outside and instead of protecting Jennings from a big hit, he forces him into a circus catch as he spins around to snatch the ball below his hip.

In the same game, we got Jennings' first contested drop of the season. This play went down as a contested drop rather than an open drop because of the defender who is in front of Jennings and affects his view of the ball. More importantly, it goes down as contested because it wasn't an easy reception. Jennings got his hands on a pass that many receivers in the league wouldn't have even reacted to in time to watch it hit the ground.

Jennings repeatedly made impressive catches, but too often there was nothing he could do to salvage the play.

On this play, Jennings beats the slot cornerback early in the route so that he is running free towards the pylon at the back of the end zone. Ponder throws the ball to the goal line when he should have pushed it further down the field. If Ponder was intent on throwing the ball to this spot, he needed to put more velocity on the ball to get it there before the defender could recover. Jennings adjusts to the ball very well and attacks it at its highest point, but the defender is able to punch it out of his hands as they fall to the ground.

On this play, Jennings runs an incredible route that completely takes the cornerback out of the play. Jennings is running parallel to the goal line across the 11 yard line. When he catches the ball, he is standing in line with the 12 yard line because he had to work back to the ball. Not only did Ponder throw an inaccurate, slow pass that allowed the defensive back time to recover, he was late to let the ball go as he didn't throw with anticipation. Jennings still gained seven yards on this play, but an effective throw would have given him an easy a touchdown.

A touchdown his route deserved.

When Cassel was throwing Jennings the ball instead of Ponder, he was still off target too often, but less often. What Cassel did do was give Jennings more timing throws that arrived accurately. This allowed Jennings to make more comfortable catches and set himself up for yards after the catch with greater ease. In fact, Cassel's first completion to Jennings immediately highlighted the difference between he and Ponder.

Jennings still has the speed and quickness to outrun defenders in the open field, but the key to this play is Cassel's pass. It arrives perfectly on time in a spot where Jennings can work through it back infield. Because Jennings didn't have to adjust or wait for the ball, he is able to take Cortez Allen, the arriving cornerback, completely out of the play.

Against man coverage, Jennings primarily relies on his route running to create separation. 38 of his receptions in 2013 came against man coverage and went for 484 yards and three touchdowns. As an experienced, technically sound receiver, it's also no surprise that Jennings knows how to find soft spots in zone coverage.

On this play against the Carolina Panthers, Jennings breaks off his out route to settle down in between two zone defenders. Cassel lets the ball go on time so the defenders are unable to close on him before the ball arrives.

Even though Teddy Bridgewater will be a rookie and hasn't played in the NFL yet, his skill set projects very well for any potential match with Jennings. Bridgewater proved to be an anticipation thrower in college with exceptional accuracy to intermediate routes. He understands how to move his eyes from receiver to receiver while managing the pocket. If Bridgewater can translate to the professional game during his rookie season, then he should dramatically aid Jennings' potential to produce.

If Bridgewater doesn't play and Cassel is the starter, he should at least be able to significantly improve on his output from last season.

A big reason for that should be the addition of new offensive coordinator Norv Turner. Turner is known for getting the most out of his tight ends, so Kyle Rudolph should feature heavily for the Vikings next year, but moving away from Bill Musgrave's offense should be very beneficial for Jennings also. In one game last season, Jennings caught three separate passes that went for no gain. Musgrave kept running the same play that the defense had clearly focused in on. A play that saw Jennings run behind the line of scrimmage to catch the ball in the opposite flat.

Those kinds of plays and screen passes that were terribly designed and timed didn't put Jennings in the best position to succeed.

C.J. Spiller

Much was made of C.J. Spiller's potential during the 2013 season because of comments made during preseason by new offensive coordinator Nathaniel Hackett. Hackett suggested that he was going to give Spiller the ball until he threw up. After a few weeks of the regular season, it became clear that what was intended wasn't what would happen. Spiller struggled during the first four weeks of the regular season as he faced suffocating run defenses behind a completely overwhelmed offensive line. In Week 4, he suffered a high ankle sprain that would completely alter his season.

Spiller was supposed to be the focal point of the Bills offense, but when the interior of your offensive line is amongst the worst in the NFL and you are dealing with a very serious injury, it's tough to carry the load. The 25-year-old finished the season with just 235 total touches. 235 muted touches.

Playing through a high ankle sprain is an unwise and unenviable exercise. Spiller would have been in pain every single week and his explosiveness was clearly limited. As a back who relies on his explosiveness, it's the kind of injury that was always going to derail Spiller's season. He was still able to make some plays, but he needed significantly more help from his offensive line to get to space and the second level. Help that his offensive line couldn't give him.

This play comes from Week 1 when Spiller was fully healthy. He is lined up in the backfield next to EJ Manuel and will be taking the ball to the right side of the offense behind zone blocking.

Initially, it looks like the Bills offensive line is winning each of its blocks and is going to set up a clean route for Spiller to attack the secondary. Spiller is making his read off of Vince Wilfork in the middle of the defense. At this point, it appears that Wilfork is on the outside shoulder of the left guard, so Spiller should be looking to run past his other shoulder.

Center Eric Wood is getting a good block on the second level, while right guard Kraig Urbik appears to have sealed off the outside of the running lane. Wilfork still appears to be shaded to the outside of the left guard, Colin Brown, so Spiller plants his foot quickly and pushes himself into the clean running lane.

Wilfork closes through Brown as if he wasn't there and collapses on top of Spiller at the line of scrimmage. Even though there initially appeared to be space for Spiller to work in and a clean running lane, Wilfork was never actually blocked out of the play. He was always in control of his positioning against Brown and swatted him aside like a bug. Now Wilfork is one of the best defensive tackles in the NFL, but this play said more about the inability of the left guard. This kind of play routinely occured for the Bills last season.

Spiller regularly had nowhere to go when he received the ball and was being asked to answer a question that had no right answer. On this play it was only one block that ruined the good work of everyone else, but the offensive line didn't just have one weak link. Regularly there were multiple missed blocks on plays.

Although he was stopped for a loss on this play, Spiller was just one block away from a huge run. He immediately recognizes that the design of the play is ruined by penetration to the left side, so he works back to the right side. There is a running lane over the middle of the field, but he needs to drag the defenders towards the opposite sideline to stop the defensive tackle on the left hashmark from doing what Wilfork did on the previous play. He sets those defenders up perfectly before cutting back to the original running lane, but by this time the other defensive lineman has come back across to close off that lane after knocking his initial blocker to the ground with ease.

Incredibly, Spiller averaged 4.6 yards per carry under these conditions.

He sustained this average with his explosiveness. Even with a high ankle sprain, Spiller was still able to outrun defenders in space and make defenders miss when he was given some blocking. He had nine runs for 20+ yards and four 40+ yard runs last year. Those nine 20+ yard runs were three less than he had in 2012, but more than the previous two seasons combined. In 2012, he had five 40+ yard runs, one more than 2013, but he didn't have a single one during the first two years of his career.

In spite of his injury and his blocking, Spiller tied LeSean McCoy, Matt Forte and Frank Gore for the second most 20+ yard runs in 2013. They were all just one behind the sole leader, Alfred Morris. Only Matt Forte had as many 40+ yard runs as Spiller did in 2013 as both finished first with four. Only five backs in the whole NFL managed more than two.

With better blocking, Spiller has the ability to be an effective between the tackles runner who can average over four yards per carry without the big plays. As last year proved, even when he isn't at 100 percent, he still has the ability to create those big plays also. With better blocking, those big plays would be nice complements to consistent production rather than the base keeping his average afloat.

Outside of bringing in Sammy Watkins and Bryce Brown, the Bills primary focus of this offseason was retooling their offensive line. Veteran Chris Williams was signed to hold the left guard position entering training camp, but fifth round pick Cyril Richardson and seventh round pick Seantrel Henderson will likely be given every opportunity to compete for the starting spot in between Glenn Cordy and Eric Wood. Left guard and right tackle were the Bills' most problematic spots upfront last year. A competition should decide left guard, but the right tackle position is Cyrus Kouandjo's to lose.

The Bills selected Kouandjo in the second round of the 2014 draft. He is a very talented offensive lineman who likely fell in the draft because of health issues rather than his ability to be an immediate starter. Kouandjo should be able to be an effective right tackle in spice of the struggles of first round picks from last season who swapped the left side in college for the right side in the pros.

Spiller doesn't need these new additions to be dominant performers. He is an exceptional talent at the running back position who only needs average or even slightly below average run blocking to be one of the most productive backs in the NFL.