Baserunners allowed to wear jackets?

Reading other answers, I was bit surprised.

I didn't know everyone is allowed to do it. I thought only pitchers are allowed to do it.

The purpose is to keep their pitching arm warm. Not just for the performance reason on the night but also to prevent unnecessary injury. After being exposed in the cold while on base as a runner, if they throw pitches hard as they do, it can cause injury to their arm/shoulder. Similar idea they cover their pitching arm with a jacket when they are in the dugout when his side is at bat. I'm sure you have seen they put a jacket on not wearing properly but covering only the pitching arm

You see this alot when pitchers reach base it helps them keep warm and therefore loose while running the bases. Not sure what the exact rule is but it happens all the time, at least when the weather is colder

Any base runner can put on a jacket but realistically only pitchers do it.

Yeah, as stated, only pitchers do it. My best guess why? Maybe because they need to keep their arms warm. Maybe their arms perform better when they're not constantly exposed to the cold.

Obviously, it's allowed, but really only pitchers do it. Don't know why.

Extremely good question, hopefully we will get some good replies

Lee can do whatever he wants.

great insightful answers, thank you