As a player who was used primarily as a bench player, Throneberry enjoyed his most playing time at 1B for the expansion Mets. After going 0-9 for the Orioles prior to his trade to the Mets, he was slotted in playing just about every day. In 116 games, he hit .244 (87-357) with 11 2B, 3 3B, 16 HR and 49 RBI, all career highs. He did hit .250 (59-236) for the Athletics in 1960. Though Gil Hodges was the starting 1B on opening day, it was obvious Throneberry was a better option at this point in their careers. Marv was a decent hitter, but on a bad team, more could be expected from everybody.
What killed Marv was his defense. He made 17 errors at 1B, which led the National League. Marv at 1B signified everything that was wrong with this team. Of course, he was brought over because of his connection to manager Casey Stengel with the Yankees. Because of his lack of everyday playing time prior to 1962, it hadn't become evident how bad a defender he was at the position. But, 1962 was his best MLB season, which is something that could be said by few others on the 1962 Mets. He would manage just 14 ABs with the Mets in 1963, before being sent back down to the minors for the remainder of the season. This seemed to devistate Throneberry, who hit just .176 for AAA Buffalo. After going 1-12 for Buffalo to start the 1964 season, Throneberry hung it up for good.