1. Crisp certainly established his reputation with highlight reel Web Gem plays, which, while certainly take some talent, are not necessarily indicative of being a good defender.
2. His defensive reputation was probably also bolstered by following Johnny Damon and occasionally alternating with Jacoby Ellsbury. If you can catch a cold on a rainy day, you can look good against that crowd.
Coco may have been overrated, but I'm not always sold on watching televised games for outfield defense, mostly because that heartless bastard who directs the telecast always waits until the ball is midflight and the outfielder is in mid-pursuit before cutting to him. But Crisp did come from Cleveland with questio marks surrounding his defense, and was moved from CF to LF because of them. (Along with the emergence of Grady Sizemore, which certaily factored in.)