Which is correct?
#1 - As an experienced pool player, I can usually sink four or more balls in a row.
#2 - An experienced pool player, I can usually sink four or more balls in a row.
I used to think #1, but I’ve seen examples like #2 a few times lately. So, is it #1, #2 or both?
Both are technically correct, but number 1 is preferred. Number two is a bit awkward, but nothing is really wrong with it.
It’s a matter of style; however, I think when refering to yourself, the inclusion of the “as” helps the sentence flow.
If you were refering to someone else, you could omit the “as”:
eg: Jim, an experienced pool player, can usually sink four or more balls in a row.
Using as in the first construction makes the cause-and-effect relationship explicit, which makes it a little redundant in the sentence you give as an example. You would definitely want to use it, thought, if you were stretching cause-and-effect to its limits for some effect.
