Thomas was derided as just a "platoon bat" going into the trade deadline and so Rizzo could not get the kind of value he wanted to move him. Well, there might have been something to that prior to August, or at least it might have appeared to be something, because his July numbers against righties were awful - .237 / .280 / .316, with 28 K% and 5 BB%. wRC+ of 62, wOBA .263, with a BABIP that was actually high - .321.
If any GM tried to shake Rizzo with those numbers in negotiations, Rizzo was sharp enough to say FUggedaboudit. Same stats for August:
.250 /.316 /.500, 32K% 5BB%, wRC+ 117 wOBA .345, BABIP practically unchanged - .325.
Streaky, perhaps, but there's a big, big jump in contact quality as he pulls less (a Davey hitting lecture):
July - 56/22/22% pull/center/oppo, 29/48/24% soft/medium/hard contact%,1.93 GB/FB.
August - 41/29.5/ 29.5% pull/center/oppo, 9/50/41% soft/medium/hard contact%, 0.48 GB/FB.
Looks like his slump against righties in July was due to hitting a lot of grounders not particularly hard, and the August spike is due to using the whole field and generating hard hit balls in the air. Not too sophisticated an analysis, and small numbers, but it seems like he may have made an adjustment to address his "Platoon Bat" rep.