If you read between the lines of what Doc Rivers said yesterday, you can tell they were already working on bringing in Barbosa.
"We're always looking. Every team is always looking. If nothing comes, does that bother us? No. It'd be great to get another guy at any position. Obviously, at [point guard] it would help, but we can't also forget that Avery [Bradley] is coming back too. We don't want to overdo the point guard thing."
Basically this is a lot like the draft in which you get talent first and then figure out how to fit it all together later. Is Barbosa a pure backup point guard? Nope. But having too many talented combo guards is a problem we're willing to live with.
Doc Rivers hinted at Barbosa signing yesterday
Celtics Blog | Oct 17