Just some general thoughts on where the Mets are and what I would do to try and fix things...
1) Go to a six man rotation. Verlander is 40 years old. Scherzer is 38. Carrasco is 36. Quintana is 34. Senga is used to pitching once a week. They will all benefit from more rest. It will allow them to go deeper in starts, I think it will improve the quality of their starts and it should make them less likely to get hurt and have to go on the IL again.
Here is the rotation now:
Scherzer
Verlander
Senga
Carrasco
Megill
Call up Lucchesi, who has been pitching well in Syracuse (just threw a shutout), and make him the sixth starter for now. He is 5-1 in Syracuse with an ERA of 2.30. He needs to be pitching in NY, if not as a starter than as a reliever.
Quintana is about to start making rehab starts and I think is only 15 days or so away from joining the rotation. Assuming that happens, and assuming he is effective, make him the sixth starter and take whoever is struggling the most (Megill probably) and either send them to Syracuse or add them to the bullpen.
2) Move Alvarez from the 2 hole in the lineup. He is a terrible fit there and I think he is hitting a lot worse since he was moved there.
3) Play Narvaez as the DH against right handed starters and Escobar as the DH against left handed starters.
For now, Canta is the first baseman and Pham in the left fielder. Let them play every day and when Alonso returns, play the one hitting the best in LF.
4) Return Vientos to Syracuse. He looks lost playing once a week and needs to play every day. It is a shame he was called up when there was no intention of giving him regular at bats. Put him back in Syracuse so he has a chance to develop further and so he is ready if there is another injury.
5) Play McNeil at 2B. Sorry, Guillorme is not the answer there. I know Buck likes him but it is time to play the best players.
Glad to see Walker called up. I hope he is kept in NY for a long time. He has really good stuff and throws left handed. That should be sufficient to keep him on the Mets for a long time.