In offensive lineman David Diehl’s case, it’s the only reason he still has a roster spot on the New York Giants.

The Giants announced yesterday that they had reached an agreement to cut Diehl’s salary from  a base of 4.475 million to 1 million. The move helps lower Diehl’s cap hit from 6.825 milion to 3.125 million.

On the surface, it’s a justifiable move. The Giants needed cap space and while Diehl ideally wouldn’t be the starting right tackle again, he can still function as a versatile backup, being able to play multiple positions on the offensive line.

There are a few major problems with this line of thinking. The first is that versatility only exists if the player is able to play the named positions at an adequate level. Diehl has proven that he is unable to play at even a below average level at any position.

Pro Football Focus ranked David Diehl as the worst pass blocking tackle in football from 2009-2011. Diehl gave up 116 pressures on only 1,191 snaps. That means on 9.7% of his snaps as a tackle, he allowed Eli to be hit, sacked or forced him to get rid of the ball quickly.  PFF’s number doesn’t even account for the fact that Diehl had extensive snaps at left guard during that time.

In 2012, Diehl was slightly better but still very much a liability at right tackle. He was far from the only problem with the Giants offense but it should not be taken as a complete coincidence that two of the worst Giants offensive games of the season (Week 1 vs the Dallas Cowboys, Week 9 vs the Pittsburgh Steelers) came with him as a starter. It also shouldn’t be taken as a complete coincidence that the Giants offense played much better after Sean Locklear replaced him in the starting lineup in Week 2.

Even after the Giants offense more or less flourished under Locklear, the Giants still put Diehl back in the starting lineup. The reasoning? “You don’t really lose your job because of an injury” according to Giants offensive line coach Pat Flaherty. Ignoring the fact that it happens all the time in the NFL, the Giants were playing at a higher level with Locklear than Diehl. The Giants took that as a blip and not indicative of something more.

If Diehl were being brought back as a strict backup, this move would not be so troubling. That’s the problem: Barring another draft pick or free agent signing, Diehl will be the starter at right tackle. 2011 fourth rounder James Brewer is viewed as a possibility to start but barring an injury or disastrous preseason, Diehl will start. That’s because the Giants organization views him as an asset and not a liability.

Giants coach Tom Coughlin publicly stated he wanted Diehl back, as did co-owner John Mara. It’s unlikely that the Giants would have been so public about a player they view as a backup.

Diehl represents a major blind spot for the Giants organization. They were quick to jettison Ahmad Bradshaw, Michael Boley, and Chris Canty this off-season. In the past, they’ve let veterans like Antonio Pierce, Shaun O’Hara and Rich Seubert go when it was clear they were past their prime. Diehl is long past his prime and actively hurts the Giants offense when he sees the field. Giants fans can see this. Impartial observers can see it. Advanced statistics spell it out clearly. Yet for whatever reason, the Giants organization just doesn’t see it that way.

It’s also not as if Diehl’s problems were solely on the field. Last June, Diehl was arrested for driving while under the influence of alcohol. Many players better than Diehl have seen their careers turned upside down for crimes less serious than that.  Diehl received no reprimand from the Giants and it was essentially swept under the rug.

At age 33, Diehl is more likely to see his performance get worse rather than better. With Eli Manning at quarterback, the Giants offense will always be better than average but their potential will be always be limited by Diehl. There’s only so much a quarterback can do when facing constant pressure from pass rushers.

In the end, the Giants season won’t be defined by their right tackle, it will be defined by how their offense and defense as a whole perform and whether or not they make the playoffs. If they fail to do so, the Giants organization will ask what went wrong and will look at every aspect of the team, including the offensive line. It’s a good bet they won’t look in Diehl’s direction though.

Aug 2, 2010; Albany, NY, USA; New York Giants defensive coordinator Perry Fewell holds up a play card for his players during training camp in Albany. Mandatory Credit: Noah K. Murray/THE STAR-LEDGER via US PRESSWIRE

As OTA’s get started and training camp right around the corner, what are the keys to watch for this season? For the Giants to get a playoff birth and make another run at the title they will need to fill the holes of outgoing players and upgrade at a few other areas.

1. Who will be the Victor Cruz of 2012? When Steve Smith departing last offseason there was a huge question mark at the WR position. Thankfully out of virtually no where Cruz emerged and had a monster season finishing behind only Calvin Johnson in recieving yards in the NFC.  With Mario Manningham gone to the left coast and now a question mark on Hakeem Nicks season the WR position has yet again become a problem area. So, who will step up? As of now we have Cruz, Domenik Hixon coming off injury, and rookie Rueban Randle as the likely top 3. After that it’s  Ramses Bardan and Jerrel Jernigan both of which have yet to show any promise. Hopefully Nicks can return to form by week 4 or 5.

2. The linebacker position seems to be the opposite of last year at this time. With Chase Blackburn being re-signed and emerging as a force in the middle and the signing of Keith Rivers from Cincinnati really will solidify the LB corp with Boley and Kiwi flipping between LB and End. And the experience that Williams, Jones and Herzlich gained last year filling in now makes this a strength and no longer the weak link of the defense.

3. The running game had an extremely lack luster year in 2011. Being non existent for most of the year only emerging in the latter part of the regular season and the playoffs, mainly due to the respect for Eli and fear of the big play, needs to be better. With Jacobs joining Manningham in SF and DJ Ware and Da’rel Scott showing very little last season it was clear that Bradshaw would need help. The Giants turned to the Draft and picked David Wilson. With Bradshaw always fighting injuries from his running style and Wilson being a rookie it would appear the G-Men will probably go to a 3 headed running attack with Bradshaw, Ware and Wilson. But this area will be a question with only 1 back That is battle tested.

4. The Offensive Line had an up and down year in 2011, giving good protection in the passing game and poor run blocking. The one constant on the line has been and will be Chris Snee at right guard. With Kareem McKenzie not being re-signed mean that Will Beatty and James Brewer fighting for right tackle, off season signing Sean Locklear with provide depth. The left side appears it will be David Diehl at LT and Kevin Boothe and Mitch Petreus battling for RG. Petreus would add needed toughness and help for the running game. David Baas had a rough start, but seemed to settle in at the center position nicely.

These questions should be answered by the end of training camp and will be key areas that will need to be solid for the Giants to make another run to the playoffs and possible championship.