Jacob deGrom had a strange first half for the Mets

Jacob deGrom has been the Mets’ lone pillar of reliability in what can only be described as a ravaged rotation. There has been a litany of injuries that have either derailed seasons or delayed them from getting started in the first place. And even when the pitchers have pitched, the results have been largely unimpressive.

deGrom’s 17 first-half starts lead the team, and his 111 innings pitched lead the Mets by a whopping 35 innings. Despite his heath and reliability, he has had a very strange and un-deGrom-like first half performance.

deGrom has a 9-3 record, but his numbers tell a largely different story. His 3.65 ERA is easily a career-worst, as is his 3.97 FIP. He has not been the lights-out Cy Young contender that he has been previously. He does have a 3.34 xFIP, and a 3.60 SIERA, both lower than last year’s marks.

His BABIP is exactly on his career average of .292, and his left-on-base percentage is just a tick higher than his career 79% at 81.2%. He is not getting any more or less lucky than he has in previous seasons, so what is the difference for this version of deGrom compared to other ones, and have the changes been all bad?

To answer the second part of the question: no, there have been some legitimately good changes for deGrom this year. He has missed more bats than ever before, has his SwStr% (swinging strike rate) of 14.1% is nearly two percentage points higher than his career average. In general, his contact percentage is down to a career-low 70.8%—it has never been lower than 75.2% in any major league season. This, as one would expect, has led to a rather significant rise in strikeouts.

deGrom has always been a good strikeout pitcher, including a 205-strikeout performance in 2015. However, this year has seen his strikeout numbers rise to new levels. His strikeout rate has risen nearly two percent over his career number, to 28.4%, and, in turn, has seen his K/9 rise to a gaudy 10.54. His strikeout rate is tied with the Yankees’ Luis Severino for eighth among all qualified starters, making him one of the better strikeout pitchers in the first half.

This sounds like all positives, but there have been some drawbacks to his game as well.

deGrom’s walks have risen along with his strikeouts. He has a career-high 8.3% walk rate nearly two percent higher than his career number. This has seen his BB/9 rise to 3.08, the first time it has ever risen above 2.76. His walk rate is right around the league average 8.6%—he is not walking people at an exorbitant rate, but it is not what we are used to seeing from deGrom.

The biggest differences for deGrom this year are when he gets hit. He has a hard-hit rate of 35.6%, five percent higher than his career number, and four percent higher than his previous career high. He is also giving up a ton of home runs, which is likely the largest issue for him in the first half.

He has already given up two more home runs than his previous career high of 16. His HR/FB (home run per fly ball) ratio is a gaudy 19.6%. His career high before this season was 11.1%, and he put up a sub-10% HR/FB ratio in his first two seasons. The league average is 13.7%, which he blows out of the water.

The rising home run numbers explain his abnormal FIP—but they also explain why his xFIP is lower. xFIP is rather forgiving to home run rates, and considers them to be “unstable over time” according to FanGraphs. So, while FIP will ding deGrom for his home run spike, xFIP expects him to regress to his norm.

He is missing more bats than normal, but he is also giving up much harder contact than normal—it is quite a strange season for deGrom.

He has also been rather inconsistent within the season itself. In 52.2 innings at Citi Field, he has a 2.56 ERA, a 3.36 FIP and 3.48 xFIP. Opposing batters are hitting .195/.292/.333 against him at home. In 58.1 road innings, his ERA jumps to 4.63, with opponents hitting .262/.302/.465. He has a road FIP of 4.52, and a road xFIP of 3.21. He has an extremely high HR/FB ratio on the road, 25%, which explains the huge difference in FIP and xFIP—his home HR/FB rate comes in at 12.5%. He is getting hit rather hard on both the road and at home (35.8% and 35.5%, respectably).

His road and home splits are not the only sign of inconsistency for deGrom. His month-to-month splits have also varied somewhat wildly.

April: 2.84 ERA, 3.05 FIP, 2.88 xFIP
May: 4.95 ERA, 4.22 FIP, 3.50 xFIP
June: 2.75 ERA, 3.51 FIP, 3.50 xFIP

He has only had one start in July, but it followed the seasonal archetype of good month, bad month, good month, bad month, as he gave up four solo home runs in seven innings in a win over the Cardinals.

The first half, on the whole has seen deGrom be an above-average pitcher—his ERA-, FIP-, and xFIP- are all below the average 100 (89, 92, and 80, respectably). Despite that, the season has been an unusual one for deGrom. His swing-and-miss stuff is the best it has ever been, and he is racking up the strikeouts, but he is also getting hit much harder than normal, and giving up a ton of home runs—even more than the league average, in what is a home-run-heavy season, to put it mildly.

deGrom is still very talented, and is still an important piece for the Mets going forward (though the Astros would like to change that, reportedly)—his 2017 season has just, simply, been a weird one for him.