But for Sanga's ton, England probably would have won the match. game certainly wasn't over when Sanga came out to bat.
I agree - England may have won that match if not for Sangakkara's ton. However, that was not in contention. Sri Lanka had no chance of winning or leveling that series when Sangakkara came out to bat (hence why I added the bit in brackets in the post you quoted). The series was England's before his innings even started so it really wasn't any different from a dead rubber innings. That was my point.