Split open Cenas head???
Are you talking about that little blood that Cena had coming out his mouth??? Iv had more blood from a tongue bite. And it was cause he is a big clumsy oaf who grazed Cena with one of his fake punches. And it honestly could have been fake anyway. If Brock had a hard time adjusting back to the ring then Cena wouldnt have gotten back up. There were reports years ago that Brock was never the best wrestler when it came to safety. Same with Mark Henry.
btw you realize that wrestlers cut their heads with razors in the middle of the ring to make their heads bleed right?
No, that was a scuffle in the build up to the fight (Brock's first two appearances ending with Cena bleeding). I couldnt find a good picture or any info on it, but heres the just of Cena's head during the match (after the GnP like 30 seconds in).
Brock didn't knock him out, so why would he struggle to get back up? It was just exsessive roughness with the elbows.
WWE wrestlers also aren't allowed to blade anymore as a result of the "PG". If anyone bleeds in WWE it's legit. You could see the cut where the blood was coming from aswell and they stopped the match to towel his head so you knew it was real.