[drdavid]

The sticky stuff on the bat shouldn't cover more than 16" from the handle. It may be 14", but I'm pretty sure it's 16".

So, while some could get on the ball, it's not very likely and it'd not be in very high quantity.

Wait, no... I decided to check before hitting the button and I'm too lazy to edit the above. I misremembered. It's 18". (Section 3.02)

https://content.mlb.com/documents/2/2/4/305750224/2019_Offic... (That's actually 2019, but I doubt it has changed. The rule has been there forever.)

The point remains the same. Ideally, you'd be contacting the ball much further up the bat. There still might be some transfer, but probably not a whole lot.

[ghayes]

You could also collect every strikeout ball and put them in a bag marked by pitcher for analysis. After a few games, you could quite easily see which had uncharacteristically higher tar on them versus baseline. That is, if the MLB actually cared.

[dreamcompiler]

Assuming strikeouts with no fouls. Which is probably true much of the time with these unhittable pitches.

[peter422]

Pitchers are putting the substance on every ball. Nearly all strikeouts are caught directly by the catcher, and the 3rd strike is the hardest to get, so it would be a very good sample indeed.