The statistical revolution in sports began among baseball fans and has made an impact across the board, but baseball is fairly easy to quantify because it's such an individual sport. As a Met fan, I know that Carlos Beltran and David Wright are independent entities; to evaluate their performance in tandem would be silly.
In football, however, it's almost impossible to separate players entirely. Offensive players rely on other offensive players to get opportunities to move the ball forward and put points on the board. Chris Snee and Brandon Jacobs are not comparable to Carlos Beltran and David Wright; what Snee does has a direct impact on what Jacobs can do.
I think, however, that the concepts undergirding the statistical revolution are far more important than the numbers themselves. With this, I have been thinking a lot about the notion of "replacement level player," and what it means in football.
A "replacement level player" provides the level of performance an average team can expect when trying to replace a player at minimal cost. In baseball, if you have more than a couple of replacement-level players, they will impact your team's ability to score runs rather dramatically. But in football, it seems to me that you can thrive with a couple of well-placed replacement-level players. I keep going back to the Indianapolis Colts. It's just not possible that the Colts have a brigade of good wide receivers who can fill in when all of their top ones get hurt at the same time. And yet Peyton Manning makes no-names like Blair White and Jacob Tamme look good. (You may also be able to add Pierre Garcon to that list. Either the Colts have miraculous scouts who can find very talented players at tiny schools, or Manning makes the players around him look really good.)
The Giants did the same thing: Derek Hagan looked pretty good when he was brought in off the streets, but how much of that was Hagan, and how much of that was Eli Manning making a receiver look good? (I come down very strongly on crediting Manning, with Hagan's value-added being a general familiarity with a complex playbook.)
A running back who avoids mistakes--think BenJarvus Green-Ellis--can produce quite well if working behind a great offensive line. BJGE isn't a home-run hitter, with a season long of 33 yards, but he was exactly what the Pats needed at running back. (He was an undrafted free agent in 2008.)
So, where does this leave the Giants with running backs? The Giants have two remarkable physical talents at running back--a bruiser the size of a defensive end, and a smaller back with elite-type agility, moves, and breakaway speed. Neither back is replacement-level, certainly. The two backs racked up 2,058 yards on 423 carries, which is stellar (4.9 Y/C). And yet the two backs fumbled 9 times, which is a clear detraction from their yardage.
I wasn't sure how I would convert fumbles into yardage-deduction, but Football Outsiders made a chart once, and based on the proximity to the goal line, you can estimate the yardage per turnover being worth 49-57 yards. The Giants lost 7 fumbles, so you could argue that those losses cost the Giants about 370 yards. Subtract that from the 2,058 yards, and now all of a sudden, the Giants' RB production looks a lot worse (4.0 Y/C).
Based on this very-rudimentary analysis, the Giants would be paying quite a bit for two running backs who were "only" producing 4.0 Y/C. The Giants' O-line, too, seems to be able to sustain lesser backs. DJ Ware got 3.7 Y/C in limited work.
If I were the Giants, I would spend resources bolstering the offensive line, whether it be in free agency or through the draft. I would probably cut ties with Ahmad Bradshaw entirely; while he is an elite-level talent, his added production just doesn't seem worthy of a high salary.
My argument is that a replacement-level back, coupled with some improvement/reemphasis on the offensive line, could produce similar levels of production at a significantly-reduced cost. The Giants should look for one attribute to emphasize in this back: ball security. The back does not need top-line speed, or great moves, or enormous size--he just needs to meet NFL thresholds and be able to survive an NFL workload. They could also target a nice fullback who can handle short-yardage situations to go with the replacement-level back. Their home-run hitters can be the extremely talented wide receiver corps they have built, potentially augmented with the return of Plaxico Burress.
I suspect that such a player will be available in the later rounds of the draft, which implies that the Giants should stay away from using a first rounder on a running back. That player may also be available on the free agent market.
So, my strategy going forward would be to look for the best-available player on the offensive line or defense in the first round, and to address the running back position with a couple of middle-tier free agents or a mid-round draft pick. I think this team is awfully close to being in the Super Bowl, and I strongly believe that if they had cut down on the mistakes this season, they would have been there quite handily. I think cutting ties with the mistake-prone running backs would be one way to signify that the turnovers will simply not be tolerated.