Chris, despite being a one dimensional fighter who had his ass handled to him 3 times in a row, indeed was (Anderson is done, so we got use past tense) a bad matchup for Anderson.
Anderson, however, dealt with a lot wrestlers in his career. In such fights he usually lost the initial rounds, until he was comfortable and beat them. Chael fights are examples.
Not saying Chris is like Chael, he aint, he hits harder (or we can just say he hits, cause Chael doesnt). Still, the fact that Chris won both 1st rounds doesnt mean AT ALL he would win both fights.
Then we saw what happened in these fights. Wrong clowning position in f1 and that kick in f2. Add age factor to Anderson, which cannot be denied.
Bottomline, Anderson fought Chris in his prime, twice. The opposite is not true.
both at their primes?
Seeing how Chris lost his fights afterwards, I would bet Anderson would KO/TKO Chris (at least) 5 times out of 10 fights. Chris would win 1 or 2 via KO/TKO and 2 or 3 decisions.
Say, 60/40 to Anderson, aka GOAT