I can't really see how releasing the infraspinatus would limit ROM overhead, same as what Breddy said. But since you said you don't think you are going overboard, maybe the issue is elsewhere? Have a go at the subscapularis as well. That can certainly limit ROM and could potentially cause some referred pain in the infra.
Personally, my subscap gets super tight but I've never had any direct pain in the area so its worth a shot. Its in the armpit area, you may have to google it to figure out how to massage it. Limited ROM overhead suggests a tight internal rotator of the shoulder, so subscapularis is the most likely cause, but could also be the pec, lats, teres major, anterior deltoid or even coracobrachialis, so give those a shot if the subscap doesn't work, but I really think it should. Let us know how it goes man.
Edit: I have never used a ball of any kind to get my subscapularis, I just use my fingers because you have to dig in too deep for a ball or foam roller to work.