I have been working with baseball fields in OSM for my deep learning/OSM project (https://github.com/jremillard/images-to-osm). My partial OSM dataset has around 13,000 baseball fields. I have discovered that around 7% of them are traced just around the infield!
If you map baseball fields, please map the entire field not just the infield.
All of OSM has over 100,000 baseball fields mapped, thats around 7,000 fields are too small. I updated the wiki for sport=baseball to recommend that the entire field be mapped rather than just the infield. In the future, I might make a MapRoulette for this. All of the baseball fields that have an area less than 100x100 ^feet are suspect.