On Thursday, with the Seattle Mariners facing a 4-4 road trip and needing a win to finish that road trip over .500, starting pitcher George Kirby gave up six earned runs in the first inning, putting the Mariners in a tough hole that they couldn't come back from.

The Mariners lost 7-4 against the Milwaukee Brewers to fall to 60-68 on the season. They remain four games back in the American League West.

For Kirby, he's fallen to 8-10 on the campaign with a 4.18 ERA. He's allowed five earned runs or more in his last two starts, and he allowed seven earned runs on July 27 against Texas.

He still has brilliance in him, as he showed in a seven-inning, no-run gem against the Minnesota Twins on Aug. 2, but it's certainly been a frustrating year for him overall.

So what's going on? It's clearly a complex issue and I don't pretend to have all the answers.

On the surface, Kirby throws hard enough to succeed, throwing between 97-99 mph regularly. His pitches move. He famously throws more strikes than almost anyone in the sport.

So for me, I have to wonder if his pitch mix is causing a problem. It's something we explored on the most recent 'Refuse to Lose Territory' podcast:

"This is George Kirby's split finger, right?

In 2024, George Kirby threw 10 percent split-finger fastballs. In 2023, when he made an All-Star team, he threw 6 percent split-finger fastballs. Last season, when George Kirby was injured and struggled, he threw 2.8 percent split-finger fastballs. This year, he's thrown one percent.

Now, is this the direct reason why George Kirby has struggled? No, but I believe that it contributes to it.

Why? Well, let's take a right-handed hitter, for instance, right? George Kirby is throwing almost exclusively fastballs, sinkers, and then curve balls and sweepers. And those curve balls and sweepers will move away from a right-handed batter, and if they're in the other batter's box or they're in the dirt, a right-hander will chase it and miss it. But if it's hung, then it's right in what we call the loop zone, and the ball has a chance to get crushed.

So that is where a right-hander can do damage against George Kirby. And if you are a left-hander against George Kirby, what exactly are you looking for and what are you seeing?

George Kirby can throw you a fastball, which you have a reasonable chance at hitting, and he'll throw you a curveball or a sweeper, and that ball is going into you. So if it's out over the plate, it's easy to be hit, and if it's hung, it's easy to be hit.

The splitter and the change-up, which we've seen Logan Gilbert throw, the splitter and the change-up are pitches that move straight down, and pitches that can, when they're thrown really well, can dive away from a left-handed hitter.

The goal is to have pitches that move away from hitters, right? So the really good sweeper or curveball to a righty, something that they can't reach and also can't lay off of, that's the goal. For a right-handed pitcher to a left-handed batter, then you want a splitter or a change-up, something that moves away from them and gets out of the barrel of their bat."

And it's not exclusive to the splitter. Kirby is throwing some more changeups this year, but it's still not a high percentage, and he scrapped the pitch entirely for a few years, which you can see below.

Either way, you have to wonder if the pitch mix is causing a problem. He doesn't have a great answer against left-handed hitting, and are his curveball and sweeper loopy enough for right-handed hitters to get a read on? Would it behoove him, this offseason, to bring back the sharper slider and the splitter?

We see pitchers work on things all the time over an offseason, as evidenced by Emerson Hancock's arm angle changes between 2025-26, so it can be done. But Kirby has to sit back and think for himself about the best way to get more consistent again moving forward.

The pitch mix is certainly our best idea at this time, though we'll have more opportunities to think about it in the offseason.

The Mariners will play the Chicago Cubs on Friday night at 7:10 p.m. PT.

The most recent edition of the 'Refuse to Lose Territory' podcast is out, talking about Kade Anderson's call-up and featuring a conversation with Mariners infielder Ryan Bliss. You can listen here, or you can watch in the YouTube player below.