AFL Pitcher of the Week Caleb Kilian Implementing Spike Curve

Caleb Kilian didn’t get much experience in the Cubs organization after coming over in the Kris Bryant trade, logging just 15.2 innings over four starts before being shut down to a COVID outbreak at Double-A Tennessee. That’s part of the reason the Cubs sent him to Mesa for the Arizona Fall League, which is often used to help top prospects make up for time lost due to injury or other issues.

For Kilian and many other pitchers, it’s also a matter of testing out new mechanics or grips. Righty reliever Scott Effross worked on his sidearm delivery in Mesa following the 2019 season and managed to parlay that added deception into a spot in the Cubs bullpen late this season. Kilian’s adjustments aren’t as drastic, but they could end up being at least as effective.

“I’m also working on two new pitch grips,” Kilian told’s Jim Callis. “They were kind of foreign to me the first outing, but they’re starting to get more comfortable and I think they’re making my pitches better…

“I’m spiking now. It used to be a regular curveball, but this one seems to be a little sharper and a little faster too. I’m trying to get a better changeup going. It was pretty average this season. It’s a circle change so I’m trying to get that perfected.”

Between the new grips and the extended downtime, it’s a little easier to understand a disastrous first outing that saw Kilian surrender seven runs without getting anyone out. His fastball has ticked back up since then to sit 94-96 mph and touch 98 to set up his cutter in addition to the curve and change. Those improvements led to a great outing in relief of Ryan Jensen and eventually to an AFL Pitcher of the Week nod.

You’ll be gobsmacked to know that slugging outfielder Nelson Velazquez took home Player of the Week honors as he continues to dominate the league.

Back to Kilian, the spike curve has been a hallmark of the Cubs’ pitching development over the last few years and it’s something to keep an eye on. The sharper break might help Kilian to be more deceptive, particularly with that hard cutter he throws.

For those who may not be familiar with a spike or knuckle-curve, they are similar variations of a grip that varies from a traditional curveball. While the goal is still to create topspin in order to create movement, the pitch is thrown a little more like a fastball, hence the added velo and sharper break. A pitcher will “spike” their index finger into the ball with the middle finger along a seam.

Former Cub Tyson Miller shows off his spike curve grip.

As the hand supinates into release, the lack of pressure from the index finger forces the ball to come out with topspin. The pitch is easy to teach and fairly easy for pitchers to pick up, particularly if they’re having trouble with a more traditional grip. Yu Darvish adopted a knuckle-curve grip in 2019 because he wanted to be able to replace the harder traditional curve he’d thrown prior to Tommy John surgery.

Darvish picked up the grip from Craig Kimbrel, who’s formed a Hall of Fame career with just two pitches, but the Cubs’ development staff has worked with several prospects to tweak their curves. Among those throwing lab-created breaking balls are Rowan Wick, Brad Wieck, and Trevor Megill, though the list certainly includes a lot more names.

Lauded mainly for his impeccable control, tightening up those secondaries and maintaining or even adding to his velocity will make Kilian a legitimate contender for a rotation spot as soon as next season. The Cubs have longed for elite strike-throwers and power arms for years now, so having both in one pitcher would be something special.

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