Who is this guy wearing Kyle Gibson’s jersey?

If you stopped paying attention to Kyle Gibson in April, I understand. He had an 8.06 ERA, 7.09 FIP, 5.24 K/9, and 4.03 BB/9 by the end of the month. Plus, he put up a 5.07 ERA last year in 147 innings with an awful 6.35 K/9. He was completely safe to ignore in all leagues. So, he sat there on the waiver wire, with no monthly ERA even dipping below 4.00.

However, if you did completely ignore him all this season, you’ve missed out on his last five starts, when things have gotten much better. Here are his numbers since 8/22 (five starts):

1.38 ERA, 2.33 FIP, 3.08 xFIP, 7.16 K/9, 0.83 BB/9, 11.6% SwStr%, 69.6% First Strike%, 3.57 SIERA, 18.4% K%-BB%.

He also did all that while still allowing a crazy high 31% line drive rate and 35% hard hit %. He’s been a huge fantasy asset during this streak. So, as I always ask, what’s going on here? What changed, and can it continue?

At first, the swinging strike % in his last five starts seemed crazy high for someone with such a low K-rate in general. However:

It’s really not out of line with what he has done previously, even this season. That was a surprise. So, a spike in swinging strikes can’t be given the credit for his recent success.

Next, I pulled up his first strike % graph (F-strike%).

Well, now we are onto something. He’s getting ahead of hitters better than ever before. That certainly explains his microscopic walk rate. If you are always getting a first strike, you have a much smaller chance of giving up a walk. This is new territory for Gibson.

I should also acknowledge luck has played a role here. Gibson has allowed just one homer during this streak. He’s near a career low (in 5 game averages) for HR/FB%, so luck has been on his side, and he’s also been helped by an 89% strand rate, well above the league average of around 70%. On the other hand, he’s allowed all those line drives and a 0.319 BABIP during the streak, so luck has worked both ways. I don’t think luck is a major factor in this recent run.

He’s throwing first pitch strikes more, what else? Well, as you might expect, he’s throwing in the zone a lot as well. I won’t overwhelm you with another graph, but his Zone% 5-game average has been up over 44% recently, which is only matched by a stretch in June of this year. That’s still somewhat low (league average is 45%), but much better than the 33-36% it was in April and July of this year and late 2016. That certainly helps his walk rate.

Another thing he is doing now is getting swings in the zone better than ever before.

When his swinging strike rate is high and he’s throwing more strikes, getting more swings in the zone is a good thing. Hitters are not punishing him for throwing in the zone more, so he keeps doing it and it is helping him limit baserunners. He’s never going to have overpowering stuff, so limiting walks is going to be key to his success. It looks like he has figured out his command recently.

How did he do it?

See if you can spot the change he made in this graph:

After throwing twice as many sinkers as four seam fastballs his entire career, he has completely switched to using more four seamers than sinkers. Four seam fastballs are known for getting whiffs at higher rates than sinkers. Further, MLB hitters are swinging upward more than ever before in pursuit of fly balls. This makes the high fastball a deadly weapon.

Let’s see where Gibson is throwing the ball.

He is throwing his four seamer higher every year, although his August and September success doesn’t exactly coincide with a spike in throwing fastballs high in the zone.

Nothing in his vertical or horizontal release points is significant. He has moved further left all season long, but nothing outside of his previous ranges. His vertical release point has been a few inches lower than ever before this year, but it has been like that all year, so no big signal there.

Without including two more graphs, I will just say that he has not seen a big uptick in whiffs/swing on any of his pitches recently. He has seen a big increase in total swings, however. The increased use of the four seam doesn’t appear to be creating an increase in swings and misses like I would expect. Here is one final graphic to show that. This is the whiff/swing rate for all his pitches over the course of the season. While his fourseam is helping, some of his other pitches have declined, balancing it out.

His pitch type change has, however, resulted in a lower walk rate and lower slugging allowed. So, in the end, moving from the two seamer to the four seamer has worked out great for Gibson, even if it hasn’t fundamentally changed his raw stuff. His stuff is still just OK, but with an elite walk rate and just enough swings and misses to keep hitters guessing, it can certainly be good enough to carry you to a championship.

Did I mention his remaining schedule?

It looks like his next start will be Sunday at home against a Blue Jays team that is not good right now (25th in baseball in past 30 days in wRC+), then at the awful Tigers, before a start to end the year against the Indians, who will probably have everything clinched by then.

This new, improved version of Gibson should be good to go for the rest of the year. How good will he be next year? That one’s tougher and it’s likely that he will just be mediocre next year, even if he maintains these changes because he doesn’t have the elite whiff rates he needs to take the next step. Tschus!