What's the matter with Twins pitcher Kenta Maeda this season?

Enough things have gone wrong for the Twins this season that no one factor is a primary reason for their 13-25 start.

Bullpen problems? Yep. Inconsistent lineup that has struggled in clutch moments? Uh-huh. More key injuries than we care to mention? Absolutely.

But I dare say that the Twins might merely be a disappointing team with a reasonable chance to rebound rather than a team in disaster territory needing to play the next four-plus months like the best team in baseball just to have a chance at the postseason if one reasonable key expectation hadn't gone awry: the pitching of Kenta Maeda.

Patrick Reusse and I talked about Maeda on Monday's Daily Delivery podcast, and let's explore his season in a little more detail now.

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A season ago, the Twins were 8-3 in Maeda's starts — a year when he finished with a 2.70 ERA and was the Cy Young runner-up. By all accounts, he was tremendous in spring training this season and seemed poised to deliver a similar season in 2021 as an encore.

Instead, Maeda has a 5.26 ERA and the Twins are just 2-6 in his starts. When you are losing 75% of the games pitched by your No. 1 starter, you are going to have problems.

Those are games a team rightfully expects to win with its projected ace on the mound. So what's going on?

*Perhaps some of it could be explained by a groin injury Maeda reportedly worked through on Sunday and has perhaps bothered him for previous starts. Even if Maeda said it's a familiar injury that he can pitch through, a small difference can have major consequences.

*For instance: His average fastball velocity is down a little this season and averaged just 90.7 mph on Sunday. Maeda is not a particularly hard thrower regardless, but that subtle dip can have an impact. The difference in his fastball and changeup velocity Sunday, per FanGraphs, was only 5.5 mph. It was on average 7 mph different last season.

A dip in velocity or an impact on the sharpness of Maeda's pitches — whether injury-impacted or not — could also explain why he's striking out just 7.9 hitters per 9 innings this season, about two less per nine innings than his career average and three less than he averaged last season. He's also walking a batter more per nine innings than a year ago. Maeda has already given up nine more hits than he did all of last season.

*That said, there could also be an element of luck at play. Opposing hitters had just a .208 average on balls put in play last season, a VERY low mark. This year, they are hitting .350 on balls in play, a VERY high mark. And Maeda was very good in clutch situations last season, stranding 80.2% of baserunners. This year, he's kept just 68.3% of baserunners from scoring.

*It could also be that batters have adapted somewhat to Maeda's pitch mix. He's continued to rely more heavily on his slider — throwing it about 40% of the time last year and this year — after using it on about 28% of his pitches with the Dodgers.

Against Oakland on Sunday, Maeda actually threw fastballs 40.4% of the time, a season-high. The A's rally in the fifth inning started with two hits off his split-changeup and slider.

Last year hitters swung at almost 40% of his pitches that were outside the strike zone. This year it's just below 30%, a marked difference that can have a dramatic impact on getting into favorable counts.

Add it up, and Maeda's struggles have had a major impact. The Twins would still be in trouble even if he was having a much better season, but let's say they were 6-2 in his eight starts instead of 2-6 — a reasonable projection based on last year and expectations. Their record, if we assume everything else stays the same, would be 17-21 — disappointing, sure, but still in the neighborhood where one good week gets a team back to .500.