When a team beats your favorite squad by 16, at various times holding a 20-point lead, you remember. And they sure as hell do. When that team is the Denver Nuggets, a sub-.500 turnover machine who until recently bequeathed Emmanuel goddamn Mudiay the keys to its offense, your head becomes like that of Linda Blair in The Exorcist. As little bearing as it has on the season and is attributable to an incongruous matchup (much like the Milwaukee Bucks always seeming to confound the Warriors), it was frustrating to see the Celtics make mistakes that, if made in the postseason, might be fatal.