It hasn’t been uncommon recently for struggling American baseball players to go spend a few years in South Korea’s KBO, then come back and produce at the MLB level. It’s a reset. It’s an opportunity to develop within more consistent playing time. Eric Thames has done it. Merrill Kelly’s done it. There are probably others I’m forgetting right now. And while neither Thames nor Kelly was all-world in their return, each produced admirably, and each did it at a bargain.
Which brings us to this year’s best free agent signing so far.
The FanGraphs/Roster Resource free agent tracker is a great resource for periodically checking in on the offseason. You can check who’s signed. You can check who’s unsigned. You can see how FanGraphs readers expected the market to play out. You can sort by any number of categories.
Two columns I like to focus on are Proj WAR and AAV. Projected War is how much WAR FanGraphs’s depth chart system expects each free agent to produce in 2021. AAV is the annual average value of each signed contract.
By dividing the latter of these—AAV—by the former—projected WAR—you can get a look at the relative value of each signing. This is imperfect. It only applies to the first year of the contract. Teams have differing estimates of how good players will be. Projected WAR is more accurately a probability spectrum, not one hard number. But this calculation is useful for seeing things like, for example, that the contract the Blue Jays signed with Marcus Semien is paying him roughly five millions dollars for each projected win he’s worth compared to a replacement player, and that this puts him at the median value for a free agent this offseason.
One interesting exercise is to do this calculation and then look at the most and least valuable contracts. To get at the least valuable, you have to do some filtering to exclude players with projected negative WAR’s, and projected WAR’s so low that the Royals are set to pay Greg Holland $160M/WAR despite only paying him $2.75M. But to get at the most valuable, you just have to look at which player’s value is closest to zero. Which, as of right now, is that of Chris Flexen, whom FanGraphs expects the Mariners to pay just $1.35M/WAR in 2021.
Flexen is 26 years old. He came up through the Mets system and has an unsightly 8.07 career ERA over 68 MLB innings, spread across parts of three seasons. He has never produced positive WAR in an individual season. But FanGraphs is high on him.
After a 21-start, 117-inning, 3.01-ERA season in the KBO, Flexen’s back stateside, and FanGraphs expects him to turn in 1.8 WAR over 130 innings for the Mariners, which would have put him among baseball’s 100 most productive pitchers in 2019. That’s solid, middle-of-the-rotation (possibly front of the Mariners’ rotation) stuff. He’s signed on a two-year deal worth $4.75M. It’s a good deal for Seattle. If it doesn’t work, they aren’t out a lot of money, but based on Flexen’s KBO performance, there’s reason to believe it’ll work. KBO competition isn’t at the same level as MLB competition, but it’s close enough to be incorporated into projections, and Flexen’s projection is rosy.
Is Flexen really the best free agent signing so far? Probably not. But best is subjective. By this objective measurement, Flexen is the most valuable free agent signing so far. And that’s pretty good.
