Bradford Doolittle, ESPN Staff WriterDec 23, 2019, 12:00 PM
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- Sports reporter, Kansas City Star, 2002-09
- Writer, Baseball, Baseball Prospectus
- Co-author, Pro Basketball Prospectus
- Member, Baseball Writers Association of America
- Member, Professional Basketball Writers Association
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The starting pitcher market has been boiling atop the MLB hot stove the past few weeks. Just check out a list of the top 20 or so starters who have changed teams since the end of the 2019 season:

Gerrit Cole, Hyun-Jin Ryu, Zack Wheeler, Corey Kluber, Madison Bumgarner, Dallas Keuchel, Cole Hamels, Wade Miley, Julio Teheran, Chase Anderson, Zach Davies, Tanner Roark, Gio Gonzalez, Brett Anderson, Jordan Lyles, Dylan Bundy, Kyle Gibson, Rick Porcello, Eric Lauer, Martin Perez, Kevin Gausman.

A few days ago, we did some estimates to create a snapshot of how wins have transferred around the majors so far this offseason. After this weekend's moves, which were headlined by the White Sox's signing of former Cy Young winner Keuchel to a three-year, $55 million deal and Toronto inking Ryu to a reported four-year, $80 million contract, approximately 191 wins have changed hands this winter via trades or free agency. Of those, 38.8% are accounted for by starting pitchers.

What's behind the rankings

To determine these rankings, we used a combination of two methods. First, we deployed the starting pitcher ranking system developed by Bill James. Then we used the Steamer projections from FanGraphs to generate scores equivalent to James' system. By averaging the two measurements, we smoothed out the data for pitchers coming off injuries and generated forecasts for pitchers not currently ranked by James' formula.

Each pitcher received an initial score based on that method. The pitchers were then ranked in order by that score to determine the likely rotation order for each club. The scores were then weighted according to rotation slot. In other words, scores for No. 1 starters counted more than those of No. 2 starters, and so on. This was done to mimic the differences in expected workloads, and also to gauge how well the rotation would rate in a postseason context. These weighted scores were used to calculate each team's rotation score.

Finally, the system generated a "slot descriptor" for each pitcher. That is based on the pitchers' overall MLB rank. The top 15 starters would rate as "first-division No. 1," for example. Anyone ranking in the 46 to 60 range would be a "second-division No. 2." The aim is to give an indication of the relative strength of each pitcher in the rotation in comparison to other pitchers who occupy the same slots.

Thus for the top-ranked Nationals, you can see that Patrick Corbin might be Washington's third starter by this method, but in the MLB landscape, he rates as a first-division No. 1. Conversely, on the bottom-feeding Orioles, Baltimore's top starter -- John Means -- rates as a second-division No. 3 starter. Which isn't what you want from your "ace."
-- Bradford Doolittle

There is still work to be done. Wannabe contenders like the Padres, Angels and Twins still need rotation help. On the free-agent market, the lefty Ryu -- who finished second in NL Cy Young balloting last season -- was the last upper-tier starter out there, at least among those who might be holding out for a big three- or four-year deal. The other top options -- think Homer Bailey, Ivan Nova, Rich Hill, Taijuan Walker et al. -- are down-the-rotation value plays, for the most part.

What do these things tells us? Well, when you've got a free-agent class nearly empty of impact starters who carry with them any degree of certainty, and you've got teams trying to compete that have rotation holes remaining, there is only one recourse. Well, there are two -- the Pacific Rim free-agent market often gets overlooked, though the top couple of options appear to have been snagged already. (That would be two pitchers out of Korea: Kwang Hyun Kim, who signed with the Cardinals, and Josh Lindblom, who signed with the Brewers.)

Basically, though, we're talking about trades. Expect the whisper mill on that front to get busy over the next few weeks. Now that we know where Ryu has landed and we wait to see which trade rumors gain traction, let's see how the rotations stack up.