Joe, I'll chime in here. Sorry if it's a bit late, but it has nothing to do with last night's HR.
Going into the season, I personally had Montero rated somewhere towards the back of a large second tier of catchers slotted behind Posey. Though it was a larger tier than typical, I felt the drop off to the tier that followed was somewhat substantial. I also drafted Montero for a handful of teams including a Main so I can relate to your frustration.
I do feel the drop was too early. Believe me, dropping him was something that crossed my mind as well, as does dropping all of my underperforming players.

That thought was quickly dismissed though, and that's because it's just too early. I think one of the biggest mistakes we can make in this game is to "overreact" to early season performances or trends, either positive or negative. In your move of dropping Montero for Buck, you reacted to both.
Just three weeks ago, you likely had Montero rated somewhere between 10 to 20 rounds above Buck. Such a limited sample size is way too small in my opinion to adjust your thought process that drastically. The reasons you had Montero rated that much higher is likely why most others did as well, ability and ceiling. Montero's was significantly higher in both regards and nothing has changed in either.
If the frustration in Montero's early season performance and especially his playing time usage by Wedge was too great, the move in my opinion would have been to pick up Buck, sit Montero for now, and to ride out Buck's hot streak for as long as it lasts. If it turned out that Buck's current hot streak was a new baseline of performance (possible considering he may be rejuvenated by being on such a great team

) or that Montero's usage becomes a season long issue, you could have dropped Montero later on when both became more apparant. In the meantime though, you would have had this high ceiling player stashed if the more likely opposite results come to bear.
Stashing a high ceiling player like Montero, especially at such a shallow position, would have been the far better move in my opinion than dropping him. It's why many are currently stashing catchers who likely have even lower ceilings for this season like McCann, Ruiz, Grandal, and even Zunino, Montero's heir apparant to the Mariners catching role.
I also think Wedge's "current" usage of Montero is not a reason to drop him. Young players are often "eased in" by their managers until their talent "forces" a greater more increased usage level. Just last year at this time, Kirk Gibson frustrated the Paul Goldschmidt owners by keeping him on the wrong side of a platoon with the immortal Lyle Overbay. Many likely considered dropping or benching Goldy at that time. However, like Montero versus Shoppach, Goldy was the far more talented player and as almost always is the case, talent won out.
Montero has the talent to flat out rake. There are also many paths to more consistent playing time as the season wears on for him to produce with that talent. After Zunino's hot start, he's starting to show he's not yet ready. Shoppach has already shown over the years, his talent level is as a backup catcher. Smoak sucks, Ibanez is old, Bay washed up, Guttierez, Morales, and Morse injury prone, Saunders injured. Montero will get his playing time and I believe will reward those patient enough to stick with him.
Those are just my thoughts on the matter. For my fantasy teams, I hope I'm right. For my Mets, I hope I'm wrong.
Good luck this year Bud and thanks for the thread. I enjoy these types of discussions.
PS - On the topic of live scoring and doubleheaders, I'll keep it much shorter... If something is promised and provided to a playing clientele, it should work correctly. I have no problem with that being both requested and expected.