Peak Rooney? Top 3 in the world.
I'm guessing the OP meant 'late-stage' Rooney?
Rooney's best 3 year period was 2009-2012 for me, and in 09/10 he was one of the truly elite players. Sánchez was close to that last season but not quite there.
The point I was making was not about their quality but about their style and deficiencies. During that 3 year period Rooney had a lot of ups and downs. I actually think he was better in the calendar year of 2011 than he was in any other year - the perfect blend of forceful creativity and explosive goalscoring. But in the first half of the 2010/11 season, right in the middle of his career peak, he managed just 1 goal in the PL and 1 in the CL.
I'm not sure why this kind of thing is being whitewashed now. Rooney was one of the streakiest elite players around and his bottom level was very low even when he was in the peak of his career. During that time he destroyed lots of attacks and failed to strike up a lasting partnership with any other forward - solo in 09/10, with Berbatov in 10/11 and with Welbeck in 11/12. They all burned brightly but never lasted.
09/10 was the only time in his career he really excelled as a lone forward. The rest of the time he struggled periodically and was moved around the forward positions. That was in large part because of his need to be at the centre of things, despite not being the most reliable player to conduct play. At his best he did it very well but there were too many periods where he wasn't at his best, and we couldn't put him at the centre of the game. So he was pushed out wide left, or he was pushed right up top, or he was dropped a little deeper, and he was visibly uncomfortable with that but it was better for the team.
Sánchez poses a lot of the same problems. It's not clear what his best position is, it's not clear what kind of role he should take between playmaker and scorer, and it's not clear what to do with him when he's screwing up so many basic moves. Sir Alex tried all sorts of things with Rooney but never stumbled upon a perfect formula. When it got really bad, like at the beginning of 10/11 when his head was elsewhere, he just dropped him. He was that bad.
This idea that Sánchez is someone you can always rely upon is weird, but the idea that Rooney was always reliable is even weirder. We all watched and discussed his many low points.