I understand the negative comments about Mays with the Mets in 1972 and 1973. In 1972, though, he was acquired likely for his post-career contributions, and bringing some publicity for the Mets. His role was to spell Kranepool at 1B and Agee in CF.
In limited games he hit .267 (2nd on team), had an OBA of .402 (led team) a slugging percetnage of .446 (2nd on team) and an OPS of .848 (led team). He also had 8 go-ahead hits in 1972. In CF, he played about half as many innings, but he had a higher fielding percentage than Agee and threw out 3 runners, Agee had 6. Mays had a higher kill ratio on baserunners and a higher hold percentage for baserunners. Agee's range factor was 2.64 per 9 innings, Mays's was 2.59, close to Agee (was was 29 and Mays was 41)
Agee's Offensive WAR was .8 and his Defensive WAR was -.9. Mays's Offensive WAR was 1.9 and his Defensive WAR was -.04.
Bottom line, in 1972, Mays was the best centerfielder.
He slumped with Giants, but from the time he got to Mets until he did run out of gas August 20, Mays hit .288 with 8 HRs.And Mets won a higher percentage of games with him starting that they did without him.
In 1973 he, like in 1972 slumped then hurt a shoulder running against a wall. He went on DL for first time in his career. Upon his return he het .250 for 6 HRs to the time he, again in August ran out of gas.
In the NLCS and World Series, he hit .300 with two game-winning RBIs. He also has the mishaps in the field, his legs were not under him.
So, by Willie Mays standards, it was not much of a contribution. But for the Mets, he did contribute. In both seasons he had hot streaks after early-season slumps and late-season slumps.
And remember the other CF in 1973 was Don Hahn. May's Offensive WAR and Defensive WAR and Total WAR were better than Hahn. Again, as dismal as 1973 was, Mays was best CF Mets had.