Nothing is exclusively good or bad (with very limited exception)
Alcohol does act on the Central Nervous System as a depressant..this means your performance can be impaired.
It also acts as a diuretic.
So the glass of wine won't necessarily hurt you, but you need to drink 3 cups of water to make up for it and you might lose the edge in training.
However, are we not also doing this to have a good time?
So, I have a bottle of Organic Frey Wine from Mendocino, a Petit Sarah 2003...and you are all invited for a glass...except wvubill22185
you look like a friggin beast and might eat the glass..maybe you better bring your own glass
...though, we'd look sorta like clones if I had not just taken 7 years off!