Cena's case is unique. Dude really got himself over on the strength of being on the show with the better, more selfless workers with better creative that allowed him to grow as a performer. The Brock feud was huge for him. Felt like he got that look out of nowhere. The match wasn't special but he basically built the framework for the rest of his career with that. The stuff with Eddie, the Taker feud.
What I will say, is that the Umaga match gave birth to BIG MATCH JAWN and was his coming out party as a genuinely great worker. Dude was getting nothing but hate from August '05 until Jan '07 when everyone outside of lunatics had to put some respect on what he was capable of in the ring.