Happy to announce that I joined @TJStats as a writer on MiLB as a whole! Rangers specific content will continue as well, so don’t worry there. My first piece is on the addition of new types of fastballs in top prospects across the league, I hope you enjoy!

Jack Leiter’s day is done in Colorado after a shaky end to what looked to be a strong start. Jack pitched 5 innings, allowing 7 hits, 4 runs, 2 walks, and struck out 7 on 83 pitches. To be quite honest I felt like Jack only made a few mistakes this afternoon, but unfortunately he never got away with one and was punished every time. The first inning he really only had one mistake on the slider to Rumfield. The pitch call itself is fine, but after a first pitch down and in cutter you really need to make sure you hit your spot of further inside and unfortunately Jack just left it right over the middle of the plate. Sometimes you can get away with mistakes like that if the pitch has any protection, but there was nothing of the sort today. The cutter and slider are both mid-speed pitches. You can get away with leaving a slider over the plate if you’ve sped the hitter up with a fastball or slowed him down with a curveball. Going from mid-speed cutter to mid-speed slider there’s just no margin for error. Jack did settle in after that and struck out the side in the 2nd albeit falling behind to start each at bat. He was really in command of his sinker and slider and it looked like it had hitters off balance just like Rocker had done last night. An 8 pitch 3rd inning helped him stay in good shape with his pitch count as well. The 4th inning is where things started to go awry for Leiter. Starting with the at bat to Freeman he just made a poor 2-2 pitch. It was similar to the Rumfield single in that Jack landed a really nice slider on the outside edge, and just followed it up with another slider but in a much more hittable location right over the plate. It’s pretty clear Jack wanted to try and get the chase with a slider further off the plate, but he just missed. Back-to-back 1 pitch outs afterwards did make you feel like he was going to continue his efficient pace. The Tovar single was just more of the same. Correct pitch with poor execution. A slider off the plate for a ball followed by a sinker. It’s absolutely the correct pitch, but he just didn’t get it in on the hands enough and was too far over the middle of the plate and was able to be hit for a single. The Julien walk I felt was messy from both an execution and a pitch calling standpoint. First pitch cutter inside is fine and a good pitch call. I did not agree with back-to-back changeups after that. I’ll go into why I don’t like the changeup at altitude later, but for now we’ll stay focused on the 4th inning. Being down 3-0 just left Jack in a poor spot and even with solid 3-0 and 3-1 pitches he walked Julien and loaded the bases. The Karros walk I can live with, as it was a good battle and Jack made a good 3-2 pitch it was just off the side of the plate and walked in a run after a successful ABS challenge. Another 7 pitch at bat then led to the elusive 3rd out, but it was definitely an uncomfortable inning. The 5th inning started in a similar uncomfortable manner. It wasn’t a bad pitch necessarily, it was just unfortunate that the changeup cut on him and ended up down and in and McCarthy was able to make it to 3rd with his speed. He was able to get the strikeout of Moniak on some really well executed pitches inside and up, but allowed the run to score on simply a good piece of hitting. He threw a good 2-2 changeup that was a good 6 inches off the plate and the batter just reached out and poked it through the infield playing up. If you want to nitpick, you could say Jack could have protected that changeup better by establishing the inside of the plate more. He started to lose feel for his sinker as the game went on, and it just started to make everything feel more difficult than it needed to be. Regardless, I wasn’t mad at the pitch it was just unfortunate the way it played out. Jack got a groundout on the next batter, but the runner did advance to 2nd and was able to score on a base hit from Johnston. It wasn’t a bad pitch to Johnston either. It was a cutter perfectly located up and in that jammed him and was hit 76 mph, but was just able to find some green grass and fall in for a hit. It's the correct pitch for the situation, and it just happened to be a hit. Sometimes that's just how it goes. Jack got a 3 pitch strikeout to end the 5th, but that ended up being the end of his outing. Jack's stuff was down across the board, and that's just kind of what happens at altitude. I talked a bit about it with Rocker yesterday, but I knew it would be more impactful on Leiter just due to the kind of pitcher he is. Jack lost about 3 inches off his fastball vertical movement, which was to be expected. He also ran into some inconsistency with both his slider and changeup, both of which I also expected to happen. Talking about the changeup specifically, it's a pitch that really struggles at altitude. Pitches like sinkers and cutters are less affected due to the fact that while you will lose some horizontal movement, you'll typically see more vertical drop on those pitches at altitude which just helps them play up. That's in large part why Rocker was able to see so much success in keeping the ball on the ground. Going back to Jack's changeup, there's a similar impact. At altitude you're likely to experience more consistent drop on your changeup, but the horizontal movement is going to be much more volatile. Magnus force decreases at altitude which is what impacts side-spin on the ball and causes it to lose a lot of its run. That's why you saw multiple times today where Jack would throw a changeup, but it would just cut on him and be in a much more hittable position. The kick-change specifically relies so heavily on the axis of the ball and the type of spin imparted on the ball, that I really hoped to see very few of them today. However, that hope was diminished when I saw Jack start to lose feel for his sinker. That forced him to throw more changeups which just increased the number of chances for the altitude to play a role in today's contest. Jack is a north-south heavy 4SFB/breaking ball fly ball pitcher, which is the exact archetype that suffers most at Coors. So with that being the case, I'm going to give Jack a mulligan for a lot of the things that went wrong for him today. I can really count only 1 instance of a mistake that was purely in his control, the walk of Julien. All the other mistakes you could look at as the altitude playing a part in pitch movement which left several pitches in some undesirable locations. It won't go down as Jack's best start of the season, and I'm sure there are several pitches he'd like to have back. However, given all the external factors, I did feel like Jack pitched a good game for the most part. He could not catch a break, and every mistake he made got punished by the Rockies lineup, and that's just how it goes sometimes. Onto the next one.