The Lowdown: How Brewers Can Prey on Struggling Shota Imanaga—and Where the Risk Lies

Shota Imanaga has an arm angle problem. He suffered a hamstring strain covering first base during a start at Uecker Field on May 4, and after missing several weeks, he's been somewhat diminished since returning to the Chicago rotation. His overall numbers this year don't look bad, but he gave up 10 home runs in September alone, and another in Game 2 of the Cubs' Wild Card Series showdown with the Padres. He's gettable right now.

The Brewers know Imanaga well. Chicago half-hid him from the Crew in 2024, and he faced them just once—in late May, when they brought him back to reality after an untouchable start to his Stateside career, putting seven runs and eight hits on him in 4 1/3 innings. This season, though, Imanaga faced the Crew every chance he got, missing only the series in June at Wrigley Field while he was on the injured list. The results were mixed; the great pitcher and the great offense wrestled each other to a draw.

• May 4, The Ueck: 5 2/3 IP, 4 H, 2 ER, 1 BB, 4 K
• July 30, The Ueck: 5 IP, 5 H, 3 ER, 2 HR, 8 K
• August 21, Chicago: 7 IP, 3 H, 2 ER, 1 HR, 2 BB, 5 K

That's a total of 17 2/3 innings and seven runs allowed, good for a 3.56 ERA. That's a very respectable number, but Imanaga certainly didn't dominate Brewers hitters. Besides, the Brewers not only applied enough pressure to leave Imanaga hobbled at the end of the first outing, but won both that game and the one in August—ostensibly, the time Imanaga gave the Cubs the best chance to win. On a pitcher-friendly day at the Friendly Confines, Brice Turang knocked one through the wind to give the Brewers all the runs they would need in a 4-1 victory.

In fact, that homer is a good place to start our discussion of what's eating Imanaga, and how the Brewers might feast against him Monday night. Notice that the target was set on the outer third of the plate, in a 2-0 count, but Imanaga missed all the way across the dish, where Turang could drop the bat head on it and crush a high line drive into the bleachers. As Imanaga has spiraled recently (he had a 6.51 ERA in September and gave up another, very different homer last week against San Diego), that mistake is emblematic of what's causing his problems.

Imanaga isn't a high-slot pitcher, and his fastball gets some value from the way its riding, quasi-rising action defies a hitter's expectations due to the fact that he releases it low. However, when he's at his best, his arm angle on the four-seam fastball that fronts his arsenal is up near 40°. That's essentially a standard three-quarters release, and throughout 2024, it's what Imanaga (mostly) maintained. There's an important correlation between his arm angle on a given day and the way the fastball carries, as described by induced vertical break.

These are all of Imanaga's career starts in the American majors, by arm angle and IVB (in feet, in this image) on the fastball. I've highlighted four of them: 

• Highest and farthest right, the highest arm angle Imanaga has averaged on his heater in any start in 2025. It's lower than that of 17 starts he made last year.
• Second-highest, just above the trendline on the left side, Imanaga's start against the Brewers in August in Chicago;
• Just below and to the right of that, indicating an infinitesimally higher arm slot but less vertical climb, his start against San Diego last week; and
• Furthest left and lowest, his start at The Ueck on July 30.

In short, all year, Imanaga's arm angle on the heater has been trending down. That's crucial, because a lower arm angle means more strikes and more called strikes when a batter doesn't swing, but also, fewer whiffs and more hard contact when they do.

Lately, Imanaga has been throwing a lot more of the first two lines of heater than of the bottom three. That's how Turang was able to crack so solidly into that ball in August, and why the southpaw has been more vulnerable with the heater recently. despite a small uptick in velocity. The ball is finding the middle of the zone much more often, and running into hitters' barrels instead of hppping over them. That's (at least in part) due to his mechanics breaking down a bit.

The Brewers also got to Imanaga back in July, in that start when his average arm angle was even lower—but it was more because of the other major problem he's had lately. He's not able to leave the zone reliably with his splitter, and if you sit on it in certain situations, you can make his ears ring with it.

That day, Imanaga's splitter just couldn't dip below the zone much; he struggles to get downward action on it when his arm angle drops. Here's all the splitters he threw Brewers batters in that five-inning, two-homer outing. Notice how many they were able to foul off, and where they hit the ball fair: when he left it up and on the plate.

As you can see, he can still be nasty when he does get the splitter to dive; he drew a couple of whiffs that way. If he's not consistently going strike-to-ball with that pitch, however, he's hittable. The Brewers struck out eight times in his five innings that day, but got their pound of flesh by hitting it hard when they did make contact. With a pitcher like Imanaga, that's often the key.

It's not just that outing in isolation. Ever since his injury in early May, Imanaga has been leaving more splitters in the zone. We could see the Brewers come out with an aggressive approach again, just as they had against Matthew Boyd Saturday, because Imanaga's two best offerings—that four-seamer and the splitter that is supposed to be its partner in crime—aren't in-zone bat-missers, and he can't get out of the zone above (with the heater) or below (with the splitter) right now.

Alas, Imanaga is wily, and he'll have a counteradjustment ready. Beginning with that much better start against the Crew in August (albeit in a loss), he's ramped up his usage of the sweeper and slider to right-handed batters, so that they can't sit as easily on the splitter and the fastball away.

Much of the magic of that successful all-or-nothing approach the Brewers used in late July lies in being able to get him down to two pitches, and he's emphasizing his third offering to neutralize that idea. Brewers righties will have to be disciplined and lay off the breaking ball, keeping their focus on the outer half and seeing the heater or splitter to their barrels. That's what they did so well in July. Imanaga earned several called strikes by throwing breaking balls to the inner half against righties for the Brewers, but they stayed in their game plan and drove the ball when he threw what they wanted.

By the time team and pitcher saw each other again three weeks later, Imanaga had tweaked things. He landed the breaking balls as backdoor offerings in the outer third of the zone, especially up, forcing Brewers righties to come out of their plan and giving them too many things to contend with. The splitter worked anew, missing a few bats even within the zone and taking the sting out of Milwaukee contact low and away. Thank goodness for that mistake to Turang; it was the only significant mistake Imanaga made all day in that outing.

The onus, then, is on the Brewers to make a new set of adjustments, not only responding to Imanaga's latest but anticipating his next ones. If he can load up the outer half with the breaking stuff even to righties, he might try running his fastball in on their hands a bit to take advantage of them looking soft and away. If they're ready for that, given his arm angle problem, they should be able to get the barrel around those offerings and hit him for power. If not, they'll be tied up and in lots of trouble.

The lower slot suggests that Imanaga is slightly but importantly compromised. The Brewers should continue treating him like a wounded animal, and hunting for the moments when he shows his weaknesses. However, he's dangerous, even in this diminished state. He has the ability to use a slight alteration of his arsenal and/or approach to stymie a lineup, just as Freddy Peralta did to the Cubs in Game 1. The Brewers have a good scouting report on him, and they've forced him to make some changes. They can continue looking for the characteristic mistakes that will be especially hittable, right now, but they also need to be ready: Imanaga showed them just six weeks ago that he remains flexible and can still beat them, or at least give his team a chance to do so.