Depends on the player's age, career numbers and maybe recent 300-1,300 PAs.
I'd normally think 450-650 PAs may not even be enough.
I realize being in a pennant chase magnifies the slumps, but it doesn't change how much time a player needs to snap out of a funk.
The JBJ example is the extreme, but he got the chance to show sticking with him pays off. How many players never got that chance? Of course, his defense played into that choice, but the slump vs sample size aspect of his career still prove a point.
Just this year, Renfroe was at .485 at the end of April!
Those 19 games are more than Santana's slump. He was still at .604 after 94 PAs... which is way more PAs than Cordero got before we all were begging for his demotion.
I can find more examples. Many more.
I remember I wanted Santana called up to replace Cordero.
YIKES!
Santana has sucked while Cordero got hot in AAA. We'll never know, if we gave up too soon on Franchy's first look.