Mmm, difficult one Gord, Colin Bell was my first footballing hero, I was lucky enough to have seen him before and after his injury, but pondering your question, I have to ask myself how much I actually knew about football at such a tender age, and, the clouded view you tend to have when it comes to heroes, what you say is true, he was a shadow of his former self, however (having had the same injury myself and knowing firsthand just how debilitating it is ) to still be able to play at the level he did and not look out of place is surely testament enough to show how good he was before, and cements in my mind that I'm not looking at this with tinted glasses.
But Yaya, he was the one player I really wanted us to sign, could never understand how supposed experts couldn't see what I and many others could see (bitchiness aside), at his pomp, majestic, colossus, unique, immense are words deservedly thrown at him, to me he was one of THE greatest players in any position I'd ever seen, so, like you, with a bit of a heavy heart, I have to say Yaya JUST shades it, regardless of anything else though I'd imagine most fans would have Colin and Yaya in their greatest 11, they'd be the first names on my team sheet anyway.