For me the message and gesture is in very poor taste, but not for the reasons mentioned above. It's not that they lost, or even that they lost heavily, it's the fact that by sending this message, the players are accepting culpability. The only thing a player can be culpable of is not trying their best. Everything else, their place in the team, their selection, their recruitment, everything else is on the management team.
By accepting culpability the players are admitting that they were at fault in their only job- endeavour.
And as a result the manager lost his job (I couldn't stand him, but that's irrelevant). His sacking is therefore the fault of the players, and I think that's pretty disgusting. I wouldn't want any of those players anywhere near VP, unless they are driving past on their way to Manchester on the M6.