People who are into athletics at Wesleyan get "really" into it. The teams compete in the Division III NESCAC (New England Small College Athletic Conference) bracket (which can be learned about through its unofficial Twitter account, @inthecac), meaning it's slightly less of a commitment than at larger schools. The athletic facilities are great, and there is some school spirit—at least for the Homecoming game.
The downside to athletics, of course, is the large hipster population. This population is largely apathetic to sports and will only watch baseball games by accident because they happen to be sitting on Foss Hill and can't avoid watching. If you are an extremely serious athlete, this might not be the school for you. While sports are definitely there, they are more of a sidenote to Wesleyan's general laid-back, hippie-hipster attitude.