For me, Osborn is a modern example of the Montgomery Paradox. That is, the player becomes more and more useful as the games get harder (and, conversely, less and less useful as the games get easier).
Specifically, this type of player has absolutely bags of effort, but limited skill. However, they have an effective ability to use their extraordinary effort to act as a 'leveller'. In Monty's case, he managed to nullify some of the best midfielders in the last couple of generations (Gerrard, Lampard etc.), thus cancelling out one of the oppositions most dangerous players. Unfortunately, whilst working in exactly the same way, this had the opposite effect when we were in League One. In games where we'd be hoping that our superior quality would shine through, Monty's toe-to-toe approach would effectively mean that each side lost a player, making it harder for us to differentiate from the opposition.
For this reason, I'm slightly worried about how Osborn will fit in if we have serious ambitious to get promoted again. This is obviously based on the premise that we have other, more skilful midfield options available next year, which is far from certain.