The whole character change is interesting as there were players who moved down the tier list instead of up. Players that come to mind are Blue, Eshura, Hitaku, Ito, Keitaro, Mr. E, and Tyrant. Blue, Eshura, Hitaku, Ito, Mr. E, and Tyrant all did fine with their original mains; Blue was a Sonic player, Eshura was a Pit player, Hitaku and Mr. E played Sheik, and Ito and Tyrant were Diddy mains. Keitaro was the only one noticeably struggling with a top tier - at the time -, Diddy, and perhaps a top or high-tier - at the time -, customs Mii Brawler. What they all have in common is that they all downgraded instead of upgrading or side-grading. What's surprising is they either do just as well or even better. Blue dropped from high-tier Sonic to debatably high or mid-tier Mewtwo, Eshura still has Pit, a mid-tier, but plays low-tier Falco often, Hitaku dropped from top tier Sheik to debatably high or mid-tier Mewtwo, Ito and Tyrant dropped from top tier at the time Diddy to high-tier Meta Knight, Mr. E dropped from top tier Sheik - he still pockets her at times? - to debatably mid-tier or low-tier Marth, and the lowest drop would be Keitaro going from top tier at the time Diddy to low-tier Falco.
People can't click with any or every characters and it certainly doesn't help if you also don't like the character. If people really, really only cared about results and were capable of playing any and every character, then the only characters that would be used in Smash 4 both competitively and even "casually" would be Bayonetta, Cloud, Rosalina & Luma, Sheik, and ZSS. No Mario, no Luigi, no Pit, no Ike, no Captain Falcon, no Villager, no Samus, no Pikachu, no Greninja, no Lucina, no Zelda, and no Fox. Even that list is a stretch and it really should be Sheik-only. Fortunately, we're not heartless, calculating monsters because that would be really freaking boring. What's pools? Sheik vs. Sheik. What's grand finals? Sheik vs. Sheik. What are we going to play after school? Sheik vs. Sheik. Hey, random corporate employee, want to play Smash 4? Yeah, Sheik vs. Sheik, right? Hell yeah.