Modern fights that would have ended in stoppage if they were 15 rounders

ruslan vs algieri
maidana vs broner
garcia vs matthysse

 

Leonard-Hearns II, Tommy would of got KTFO again

 

Holmes would not have lasted against Evander.

Him throwing up on the way back to the corner showed how demanding the bout had been to an old fighter. Bad news. Holyfield and his corner would have taken advantage and Evander would have pressed on the gas in the 13th.

 

Khan vs Maidana. Khan khan khan dodging a bullet once again.

 

Well the whole pacing and nature of the fight could be different with fighters knowing it was 15 instead of 12 rounds, but here's some.

Chavez stops Taylor without (or much less controversy).

Taylor was largely winning the fight by outworking Chavez. He was taking a slow beating even in the rounds he was winning. It wasn't a great defensive performance or a pure tactical boxing display, it was an insane display of speed and workrate by Taylor. Chavez was gonna give him a bad beating regardless, and I don't think much about Taylor's strategy, or especially defense, changes with him knowing "this is going 15 rounds".

Oliver McCall-Frank Bruno. Bruno was exhausted in the 12th round, and the fight was fought at a snail's pace.