Why Patrick Corbin will be worth his $140 million from the Nationals

The Washington Nationals have agreed to sign free agent left-handed starter Patrick Corbin to a six-year, $140 million contract, Chelsea Janes of The Washington Post was the first to report.

Corbin is the first big free agent domino to fall this offseason, with the Yankees and Phillies also showing strong degrees of interest. New York entered the sweepstakes as the favorite, considering Corbin grew up in upstate New York and expressed a desire to play for his childhood team. Regardless, the Nationals’ willingness to offer Corbin an extra year ultimately tipped the scale in their favor.

Corbin, who will be entering his age-29 season in 2019, had a career year last year, posting a 3.15 ERA over 200 innings. His peripherals, though, tell a much different story. Corbin struck out 246 batters and walked just 48; his 24.8 K-BB% was a career-high by over seven percentage points, and it ranked fifth among all qualified starters.

Thus, FanGraphs’ WAR (fWAR) — which is based heavily around FIP — liked Corbin’s 2018 season. A lot. They pegged him at being worth 6.3 wins last year, much higher than his previous career-high of 3.5. Other similar metrics, such as WARP (5.9) and RA9-WAR (5.7) also saw a change in Corbin’s game. Generally, when all three WAR systems are in agreement of a player’s results, there isn’t one individual stat that may be skewing it. No matter how you slice it, Corbin had a phenomenal year, and he was just paid like a front-line starting pitcher as a result.

But, can Corbin continue his success into the future? The Nationals certainly hope so, and the evidence suggests that it may be possible for him to continue to be as effective.

In 2018, Corbin employed a philosophy known to many as “pitching backwards.” Basically, this entails throwing one’s fastball less and their off-speed pitches more.

Corbin’s four-seam fastball percentage dropped to 19.1 percent last season, after sitting at 30.8 percent in 2016 and 27.3 percent in 2017. Thus, because he used his fastball as a “weapon,” hitters struggled against it with more frequency, batting just .258 against it (a 61-point drop from 2016) and posting just a .323 wOBA against it (a 55-point drop).

And while his fastball saw great results last year, his slider benefited even more from the change. Upping his slider frequency to 40.9 percent in 2018, Corbin was able to overpower batters with a 54.6 K% and just a 4.2 BB% against the pitch. Among pitchers with at least 100 batted ball results on the slider, Corbin’s .191 wOBA against the pitch ranked 7th in the Major Leagues.

With these changes and the excellent results that came from them, it’s quite possible that Corbin will be able to sustain this success — at least to a degree — into the future.

Steamer projections see Corbin falling off quite a bit from his dominant 2018 (projected 3.5 fWAR next year), but even applying when you apply the aging curve, this deal could turn out quite well for the Nationals:

As a general baseline, one can assume that a player will be worth about $9 million per WAR over the course of a future contract. So, while Steamer only thinks that Corbin will be worth 14.5 WAR over the next six years, he only has to beat that current projection by about 1 win or so in order to make the contract for the Nationals “worth it.”

If Corbin puts out any future years that even come close to his 2018 production, this deal could turn out quite well for Washington. That’s especially true when you consider the fact that the Nationals will be deferring a portion of his contract, reducing the present-day value of it due to inflation.

As a result, you can’t hate this deal for the Nationals. In an increasingly competitive NL East division, which has seen the Braves sign Josh Donaldson, the Mets acquire Robinson Cano and Edwin Diaz, and the Phillies acquire Jean Segura (with likely more moves to come), the Nationals felt the need to get a free agent fish of their own. Adding Patrick Corbin to the top of a rotation that already includes Max Scherzer and Stephen Strasburg makes the Nationals’ pitching staff scary once again heading into 2019.

Devan Fink is a Featured Writer for Beyond The Box Score. You can follow him on Twitter @DevanFink.