if Ruiz was scared of Tyson, I think Tyson could KO him. Tyson excelled against boxers, but if Ruiz gave him any sort of resistance in 2003, Tyson would likely fold. On paper easy fight for Tyson, but it's Ruiz's fight to win if he wants it.
Ruiz should be favored, but anything could happen the first 3 rounds with Tyson's short window of explosive power.
I'm no Ruiz fan but Tyson had problems with guys that hit n held and John "Huggy Bear" Ruiz was the master at that.
Depends on the ref. If it's someone like Mills Lane who will penalize Ruiz for his fouling then Mike puts him to sleep. Mike could also blow him out in 20-30 secs like Tua did if he catches him cold right away.
Even though Tyson was shot in 2003, there is a chance Tyson could finish Ruiz early. Tyson could still be dangerous in early rounds, remember he almost finished Danny Williams off early until he tore his knee. And lets not forget what Tua another short stocky explosive fighter did to Ruiz. Although personally i think Ruiz would frustrate a faded Tyson, with his clinching style and get a stoppage late on. It also wouldn't surprise me if Tyson got frustrated with Ruiz's clinching style, and did something not in queensbury rules and got himself DQed.