Most of you probably understand the law of diminishing returns: for every additional unit consumed, the utility of that marginal unit decreases. It’s the holiday season, and eggnog is the perfect example. The first eggnog you have is fantastic, the second is good, but by the fifth, you feel sick.
Relief pitching also carries diminishing returns, not because adding one more elite reliever hurts run suppression, but because the innings in which they appear are less valuable in a relative sense.
Only about 16% of all batters faced by Yankee pitchers threw last year were high leverage, and almost half of all appearances were the lowest-possible leverage situations.
Note that this is all Yankee pitchers, not just relievers. Obviously relief pitchers tend to work in the higher-leverage spots, but full seasons from Gerrit Cole and Luis Severino should both change that distribution, and likely reduce whole-cloth the number of high-leverage plate appearances.
The Yankees, of course, have built their team around their bullpen, with splashy investments in Aroldis Chapman, Zack Britton and Adam Ottavino. Chad Green is the guy the team will likely rely on for multi-inning high leverage work, and was spectacular in that role in 2019, with a 1.95 ERA and laughable 55:5 K:BB ratio in appearances that lasted more than one inning.
All this brings me to the relief market news swirling around the Yankees since Cole signed. The team never really pursued Dellin Betances, staying on the sidelines while he inked a deal with the crosstown Mets. There have been rumors that the Yankees are interested in reigning NL Reliever of the Year Josh Hader, but the Brewers are likely asking too much for the Yankees to really bite.
Hader’s exceptionally valuable; he’s been the best reliever in the game for the last two seasons and isn’t a free agent until 2023. You can’t blame the Yankees for being so interested in a player like this, but that relative value bit probably doesn’t add up on the trade market.
The right-hander would do two things in a hypothetical Yankee bullpen: throw high-leverage innings, or work multi-inning appearances. Either way, you’re moving your high-cost, high-leverage guys like Britton into lower leverage spots, or you’re making Green and Jonathan Loiasiga considerably less valuable by restricting them to one inning of work at a time. Or, you do nether of those things, and move Hader into the regular bullpen rotation, and lose a lot of his value by making him just another reliever.
There are 30 teams in baseball that are made better by adding Hader or Betances. The question isn’t would the Yankees be better, it’s instead about the relative value, since that determines the cost the team is willing to bear. The cost of yet another high-leverage reliever probably isn’t tolerable for the Yankees, since one way or the other, they lose a lot of value when a great arm has to throw in blowouts just to get work in.