So the version of Lewis who beat Holyfield twice vs the Ruiz who went 1-1 with Joshua. I'm not sure Ruiz would even win a single round vs that version of Lewis. It would be a complete shut out as Lewis would just never allow Ruiz into range. Only version Ruiz could possibly beat would be the complacent one who lost to Rahman in 2001 and even then it being at altitude would probably be even more detrimental to Ruiz than even that version of Lewis. Plus Lewis was susceptible to right hands and Ruiz's right hand is nothing special. So I wouldn't even bet on Ruiz beating the worst version of Lewis we've ever seen.
Ruiz struggles to land a glove. See what happened V Tua. Ruiz doesn't have great feet. Gets his head boxed off. Quick hands, snappy power, good chin but can be stationary. Lewis just beat him any way he wants.
People forget that Joshua had already knocked Ruiz Jr down and was going to stop him before getting caught stepping in.
I never liked Lewis, but I respected his talent. If the pride of England-Canada-Jamaica elects to go search-and-destroy, he stops Ruiz inside of 10. Otherwise he jabs and boxes his way to a comfortable and uneventful UD.