It’s the mesh fabric that the new batting practice caps have and I think that’s totally fine with me. What bothers me, aside from the randomness of a red or blue brim, is that the starts on the logo do not reflect the flag. As you can see by the Angels logo, the Stars are not parallel to each other. It’s just randomly placed.
It appears that the home team will wear caps with the white crown and the road team will be the gray crown. The brim colors appear random, so I don’t know what correlation there is for that either.