Will Diamondbacks Rotation Woes Impact Their Playoff Odds?

The Diamondbacks took off for Milwaukee last night on a down note after getting blown out 12-3 by the Cleveland Guardians. It was their second such blowout loss during a seven game home stand, having lost to the Phillies on Tuesday 15-3. They were just 3-4 in the two series, and now must play seven road games in seven days, including three consecutive games in three different time zones.

This Thursday was originally scheduled to be an off day, but due to a cancellation caused by poor air quality, they will need to fly from Milwaukee to Washington D.C. Wednesday night to play a make up game against the Nationals. Then on Thursday night they'll fly all the way back across the country to play a weekend series in San Francisco. They'll finally catch a day off on next Monday, but then must face the team with the best record in all of MLB, the Tampa Bay Rays, for a three game series back home.

So it's a good thing at 43-29 they've managed to bank wins against weaker opponents recently. The D-backs remain in first place in the NL West, but have a new team breathing down their necks, the San Francisco Giants who are just 3.5 games back. The Dodgers are 4.0.games behind and the Padres are lurking at 7.5 games out. Full Standings page here. Checking in on the updated playoff odds we publish from time to time, the D-backs have increased their odds of making the post season by about 3% and and winning the division by 9% over the last two weeks.

All the way back in November we forecasted the Diamondbacks to be better than you think. That was before the trade with the Toronto Blue Jays to bring in Gabriel Moreno and Lourdes Gurriel Jr, shoring up the catching and adding a right handed bat to the lineup. It was also before the much improved bullpen took shape. The position player part of the roster appeared to be much strong than the pitching side. The MLB average split on WAR (Wins above replacement) generated falls between 57-59% for hitters/fielders, and 41-43% for pitchers. The Diamondbacks were projected for a 69%-31% split between position player and pitcher WAR. So far year to date, that gap is even bigger as the team has generated 14.5 position player WAR to just 4.5 pitcher WAR for a 76%-24% split.

This is all just another way to say what most observers of the team can see from watching the games and looking at more traditional stats. The offense is excellent, the defense is really good, but the pitching in total has been below average. Whereas last year the bullpen was frequently the cause of a lot of losses, most of the problems with the pitching staff this year stem from inconsistent starting pitching from anyone not named Zac Gallen or Merrill Kelly.

Kelly and Gallen have combined to go 16-5 with a 2.99 ERA and the team has a 19-10 record in their 29 starts. In the other 43 games the remaining starters are 7-14 with a 6.18 ERA. Remarkably the team is 24-19 in those games, testament to how often the lineup and bullpen have bailed out the other starters. Overall the starter's ERA of 4.72 ranks 22nd in MLB

Early in the year, when Madison Bumgarner was DFA'd after just four starts the hope was that the young starters would develop quickly and be able to pick up the slack. However despite removing Bumgarner from the roster, the team's starter ERA has not improved. In fact it has been slightly worse, at 4.77 since April 20th.

Mike Hazen tried to warn us during the end of season press conference in October that as good as Ryne Nelson and Drey Jameson looked last year over the final 4 weeks of the season, heading into the 2023 season with more than one rookie starter was a risky proposition. He went out and re-signed Zach Davies to provide some reliable innings, but it's not worked out. Davies injured his oblique two starts into the season and has been largely ineffective since coming back from the lengthy injured list stint. The only silver lining for Davies even after giving up nine runs yesterday in the blow out loss to Cleveland is that his FIP is only 4.06, and he may have been getting a bit hit unlucky.

Jameson was moved from the pen to the rotation to replace Davies but after three ineffective starts was demoted to Triple-A. He came back recently only to be converted to a relief role for the remainder of the season. Nelson has been up and down, wildly inconsistent, and is having a difficult time getting swing and miss and strikeouts. He's had four good starts, three so-so starts, and seven poor starts. Tommy Henry Has been mediocre too and much heralded prospect Brandon Pfaadt was a disaster in his first call up.

If the D-backs are to make it all the way to the post season with the current roster then clearly a lot of improvement will be needed from the rotation members. Of course with the trade deadline approaching in six weeks many are pinning their hopes on the team being able to trade for a starting pitcher that can fill the breach. A couple of weeks ago we kicked off a three part series addressing potential trade targets. The reality is the market is very difficult. As of today only seven teams are more than 5.5 games out of a Wild Card berth, and three of those teams trail their division leaders by even less than that. With only a handful of clear cut "sellers" at the moment, the market has yet to develop. Unless Mike Hazen is willing to be extremely aggressive by moving one of his highest rated prospects such as Jordan Lawlar or Druw Jones, it will be difficult to bring in a difference maker to the starting rotation any time soon.