(written from a Production point of view)
According to the first draft script of DS9: "Rejoined" (then entitled "Once Joined"), Plek'et was a type of Trill game which was similar to baseball. As described in the script, it involved five "bases" and a disc was used instead of a ball.
In the same script, it was established that Curzon Dax had once taken Benjamin Sisko to a game of ple'ket, which Sisko had enjoyed. He commented about the experience years later, saying, "It was fun, but what can I say, it wasn't baseball."