In only his second career start, he threw a 10-inning shutout in a 1–0 victory against the Milwaukee Braves, accumulating 13 strikeouts in the process. The 13 strikeouts were at the time a Mets franchise record. He had two wins and one loss in four games that season, and spent the next two seasons with the Mets as a relief pitcher. During the 1968 season, Selma again became a starting pitcher and started 23 games, posting a 9–10 record with an ERA of 2.76. This, along with his 117 strikeouts, led the expansion San Diego Padres to draft him with the fifth pick in the 1968 expansion draft on October 14, 1968.
