Welker, a former Patriot, knocked the 27-year-old out of the AFC championship game when he hit him while he was trying to cover Demaryius Thomas on a crossing route in the Broncos' win over Bill Belichick's side.
Carter told reporters: "When I saw it, just as a player in general, Wes, was he doing his job? I'm sure he was to a certain degree. I think the hit could've [been] cleaner. I've been around a lot of football to see that.
"At the end of the day, it was a nasty play. We'll see what the league does."
Welker played for the Patriots between 2007 and 2012.