Let’s Talk About FIP’s Shortcomings as Seen in Jason Hammel’s Performance

The Cubs released Jason Hammel to go free into the wild when they declined his option and didn’t extend a qualifying offer at season’s end. Doing so was a courteous move by the Cubs’ gracious front office, granting Hammel the chance to capitalize on his value in a weak pitching market.

But why hasn’t he signed?

I’ve come across a few people who think that the discrepancy between his 3.83 ERA and isolated pitching stats, such as FIP (4.48), xFIP (4.34), and SIERA (4.28), gives teams pause when it comes to offering a gooey contract (e.g., three years, $40M). But I’m not buying that argument.

Doesn’t his high FIP suggest that he wasn’t as good as his ERA? Isn’t the whole point of FIP to eliminate the defense behind a pitcher and tell us how well he actually performed? Not completely. As Tom Tango, the creator of FIP, said:

Just because FIP doesn’t consider a player’s performance on batted balls in play or with holding runners, etc, doesn’t mean that it thinks that all players are equal in those respects.

FIP is one angle. It just so happens that FIP is a huge angle, with OBP for batters is just a big angle.

One interpretive limitation of FIP is that it inherently assumes strikeout rate is 100% pitcher-independent. That, as we know, simply isn’t true. A strikeout can be influenced by the catcher, umpire, pitching sequencing, ballpark atmosphere, etc. For example, Hammel’s 22.1% whiff rate in 2016 was hardly different than his 22.9% whiff rate in 2015, yet his 2016 K/9 of 7.78 was much lower than the 9.07 K/9 he recorded in 2015. If Hammel had recorded that higher K/9 mark in 2016, his FIP would’ve been much lower than 4.48.

FIP is awesome and I love it and it makes things easier to understand, but this single metric was never meant to be the end, just one of the means to it. And sometimes I see people incorrectly centralizing their arguments on FIP in a way Tango cautioned against.

I think there is reason to believe Hammel’s FIP could’ve been better, and I think there is a chance he was as good as his 3.83 ERA. I obviously don’t know this for certain, but there’s enough gray area here to at least make you ponder.