My thoughts about the changes:
Let me start off about what I think made pit OP in 3.02. I believe his recovery and combo game was just too good. By the end of 3.02, a downthrow would lead into a combo that set up for an easy edgeguard against most of the cast, even with the general good recovery of everyone. The changes aimed to fix this, knockbacks were changed, and the downthrow changed to make pit not so easy mode in the combo game. However, one of pits weaknesses were in his neutral game (Not a weakness per se, just not OP like the rest of his kit). Spamming arrows was one way to get around this, but it's predictable. Now here is where the changes really hurt Pit this patch. 8 frames to grounded arrows and 5 frames to start of downtilt, 3 frames to start WoI (air), 5 frames to fair (2 after lag cancel). 17% slower glide. With all of these together, it really slows pits approach down, weakening his neutral game significantly. I think they intentionally hit his approach game, trying to limit the number of safe options, but now pit went from having multiple options to almost none. Of all of these, the frames added to the glide (in addition to the slow) are the most detrimental. Glide used to be a good cross up to catch your opponent off guard. It was a way to punish someone from a distance. They likely made this change to stop pit from getting a free back after grabbing the ledge, but imo, the speed should be reverted to what it was. it's too easy to see it coming now.
That being said, it's hard for me to tell the effects on pit overall relative to the rest of the cast. My roommate is a mario player (which was already one of the more difficult matchups, and mario was mostly unchanged except for fireballs and recovery) and I haven't been to a tournament yet to see vs the rest of the cast. Pit isn't a terrible character or anything, he just feels slow now. The nerfs definitely knocked him down from top tier to mid-high tier though, which was the goal.