This question already has an answer here:
See below for issues as to why the alleged duplicate (and its purported duplicate) seem to miss the point re: structure and only serve to rubber stamp poorly constructed grammar on the basis of historical misusage and longevity thereof.
IMHO, this only serves to obfuscate clarity in the language.
We have adjectives & adverbs, comparatives, and superlatives, e.g. good, better, best [never let it rest til the good is better and the better is best]
- Bill can do it well.
- Sally can do it better.
- The team can do it best.
So, why does a news anchor really mean, "as well as Bill can", when he tosses to a reporter in the field to gives us the details "as best he can"?
I would have no qualms with the idiom in "Let's have Bill give us the details, the best he can", which only means he'll do the best he can or as well as he can, not necessarily better than anyone else could.
To my ear, "as best he can" should mean the same as "as he can do it best" meaning better than the rest of us, e.g. "as the team can [do so the] best, i.e. better than Bill or Sally could.
Since when does "as best" mean the same as "as well as"? Simply preceding "best" with "as" does not demote it from a superlative.
When used as "the best he can", it's superlative standing is intact, because it is only relative to "his" capability and not ALL possible results.
In another forum such as this one, I was loudly shot down. IMHO, they missed the distinction between "as best he can" and "the best he can", the latter clearly meaning "as well as he can".
and I cannot agree with most of the convoluted justifications found here: What is the structure in “as best you can”?