He's had enough chances to make an impact and has not done the job. Marble is surging and deserves more time at his natural 2 position. May's limited skill set and energy would be better served as a 6th man coming off of the bench.
It is time to start Marble and bring in McCabe and May for Marble and Gatens early, then bring in Marble after a short break for Cartwright and keep that cycle going.
Marble is improving, May isn't... for whatever reason. Physical Injury or Mental Difficulties, he is struggling either way and it is costing the team.
Marble, Basabe, Cartwright, Gatens and Cole should be the starting line-up.
I like the idea of bringing May and McCabe off the bench too... worth trying something different.