This is a really interesting point.
On one hand you've got Miguel Cabrera in the MLB getting nearly $300 million guaranteed on a 10 year contract when he's already over 30. These signings rarely work out (see Pujols, Rodriguez), yet teams are giving them out anyway. Reportedly fellow Exec's were mad at the Detroit Tigers when they heard the length and dollar amount of the contract. These guys are definitely getting overpaid; into and past their prime.
On the other hand you've got the current NFL running back. They can excel as a starter (Moreno 1,000 yards and 10 TD's), or key backup (Starks 5.5 yards per carry), be in the relative prime of their careers, and still get paid a COMBINED $6 million over three years. Severely underpaid.
The NFL is raking in the money by the bucket-full. So where is the money going to if it's not the RB's? Their fellow backfield partner the QB. At some point though, I'd like the Players Union to step up and make this an arguing point in the next CBA. They should say "If RB's come in on your new rookie contracts and get paid minimally, then get to the open market and get paid minimally on their second contracts (likely their last meaningful one.) Yet produce meaningfully the whole time, where are their paychecks?"
The Tigers were in pennant races and won their division in 2011, 2012 and 2013. In 2012 and 2013, when Cabrera was in Triple Crown contention, they drew on average over 400,000 additional fans per year over 2011. While it is difficult to separate out the Cabrera buzz from the improving Detroit economy or other factors, there should be no question he put a meaningful number of additional butts in seats, not to mention some bump in local TV ratings, with nearly all of that incremental revenue going straight to the bottom line.
I make this point less as an argument in favor of Cabrera's contract than to highlight a key difference between MLB and the NFL.
Most NFL teams sell out regardless of who's on the field and a large source of NFL team revenue comes from pooled TV money whereas MLB TV money is still substantially local despite the national broadcast deals. At the extreme, local rights in KC are about $20 mil per year; Dodgers + Angels runs about $500 mil per year.
In the NFL, the value of $ spent on a player can be measured strictly against the players' contribution to winning. Cabrera's value to the Tigers goes beyond what WAR might tell you. This might be particularly in evidence if he remains an elite hitter for, say, 5 years of the 10 year deal and the Tigers fall out of contention for some or all of those years while Cabrera vies for one individual title or another. In particular, he might give fans a reason to watch the local TV broadcasts come August and September when the team is not winning.
Do the math...conservatively figure $50 per incremental butt-in-seat (ticket, parking, concessions, merchandise) + the incremental bump in local TV ratings.
I would question more seriously a contract like Verlander's $26 mil per year or Kershaw's $31 mil per year. Starting pitchers make at most 35 appearances and could blow out an elbow or shoulder at any time.
As for running backs in general, they are highly susceptible to injury and have a short shelf life. Moreno missed 1/2 seasons in 2 of his 5 years. We need not recount Starks' record of unavailability. Year-in-year-out durability into second contracts is uncommon; through second contracts it's downright rare.
With Lacy, we can take some encouragement in that he came to us with a lot of tread on the tires...he ran the ball only 355 times in college. One would hope we'll never again see McCarthy push him to over 30 touches in garbage time. As for his second contract, that's 3 years and over 1,000 touches (if we're lucky) down the road...extending him before well into his contract year would be ill-advised.