Hello and welcome back to FanPost Friday and oh, what a Friday it is. The Mariners are about to enter the second half of the season riding high on a 14-game winning streak, facing the Astros at a sold-out T-Mobile Park. This is the good stuff, folks. But, while we anxiously wait out the last few hours of the All-Star Break for the Mariners, let's take a look at another excellent update from flygutifly on Jarred Kelenic's AAA pitch data. Enjoy! - Eric

Happy All-Star Break! This is my third update on how Jarred’s swing decisions are trending down in AAA. Overall, his numbers are trending in a positive direction still. His plate discipline paid off with a sharp correction in his rolling CSW% (seen in the graph below). He has come a long way since he was initially sent down in May and for those that may think he is stalled; he seems to still be making positive progress. He did have some swing and miss issues specifically against change ups this week, but not enough to seriously move the needle. This week did show why the granularity of this data is important: he was able to ambush some first pitch fastballs, which inflated his results.

My writeup on Jarred’s first 30 games in AAA

Update 1

Update 2

A bit on my process from the first article: I made an Excel spreadsheet and filled a few notebook pages with tallies going through every pitch he has seen in a Rainiers uniform. I am just a human tallying pitches up and though I was being careful, it is totally possible I made some mistakes. Basically, build some error bars into these numbers and don’t take them as exact, but we are here to do trend analysis anyway. Additionally, I put splitters in the fastball bucket, whereas I believe a lot of sources count the split finger fastball as an offspeed pitch, so probably a systemic error on my part (he didn’t see too many splitters anyway). For the sake of total clarity, my buckets are:

Fastballs – four seam, cutter, sinker, and splitter

Breaking – Curve, knuckle curve, slider

Offspeed – Breaking and changeups

The numbers in the tables below are up to date through the 17th of July. He has played a grand total of 46 games in AAA, with 212 plate appearances, and 820 total pitches. Of those pitches 48.5% were offspeed (398 total).

With 46 games down in AAA, I did the first 23 games as ‘first half’ and the next 23 games as ‘second half’. I also included his most recent 10 games, which is just to show you what he has done lately with a very small sample size. I would recommend focusing mostly on the second half numbers to get an idea of how he is doing!

Plate Discipline (%)

CSW% + Whiff%

And here is a 10-game rolling CSW% graph, for the visual learners:

He was able to quickly turn around his rolling CSW% because of his improved process at the plate. I think next update there will be enough data to justify breaking the results into thirds, which I think will make the trends even more clear. The first half data is starting to incorporate a lot of his post approach change results, which is hiding how bad he looked when he first went down. I am a biased observer, but when I was going through the results, it seems like things really started to click for him around the beginning of June and breaking things into thirds will highlight that.

I will update this again on the next Rainiers off day after the break or a graduation update if he gets called up. I think it will be interesting to see how these granular plate discipline metrics translate from AAA to the Majors. As discussed in the first post, his results after his demotion were almost identical to what he was doing in the Majors before beings sent down. I don’t know of any research that has studied how these numbers translate across levels, so we are going to learn together in real time if any of this actually matters!