If you liked the Slam Dunk manga, the Anime-Planet community thinks you'd like:
Mori Buntaro transfers to Yokosuka North High School and wants nothing more than to be alone, even going so far as to ignore his teachers and brazenly skip class. But when Hajime Miyamoto challenges him to climb the school building as a form of hazing, Mori feels alive for the first time in years. Awakened to the thrill of rock climbing, he pursues his goal to reach to the sky, but can he learn to work in tandem with others, or will he be forever seeking the heights alone?
To put it simply - Mr. Fullswing is refreshed, baseball version of Slam Dunk. Both are comedy sports mangas, with arrogant main character. The protagonist decides to join a sport club, since he have fallen in love with manager. Even though he knows nothing about the sport, his raw power makes him potentially a great player.
While Mr.Fullswing sometimes have too many gags (to a point, that it gets tiresome ) both mangas are amusing sport stories. If you like one, you should give the other one a try too.