Extemporaneous speaking
Some folks are really good at doing memorized promos. The problem is, it's really hard to say someone else's words and make them sound natural. Pro Wrestling isn't Hamlet. It isn't Friends, regardless of what Kevin Dunn wants to think.
It would actually help the writing staff more if they just went with Bullet Points and an amount of time for a promo. Then the boys figure out how they want to get through the Bullet Points in their own words, how they feel like they themselves would say it.
Alas, some guys aren't good at talking at all. What do you do with folks like that? Limit their talking and let someone do the talking for them (managers). Honestly, if Managers were still a thing, Enzo wouldn't ever be anywhere near the inside of the ring.