Many people were surprised that Joe didn't get a full call-up this time around, especially given his performances wearing the captain's armband of late, but Trevor is urging Joe to be patient.
"I think Joe is now doing well in centre midfield with Michael, and he has responded to the captaincy well, but wherever you look the side has had talent - but the results didn't reflect that," he says.
"So, more than anything, if the results continue and we get away from the bottom three the international recognition will come back, and the fact that we have got five in the U21s is a major plus."
Four of them played in Friday night's 4-2 defeat by Portugal, with Glen Johnson the odd man out.
"Glen Johnson deserves it with his emergence over the last few weeks and young Michael and Joe are old hands at the U21s," says Trevor.
"They are looking to kick on into the senior side and the more they play as they did against Sunderland the more inevitable the senior call will be.
"But in the meantime, they have just got to get that consistency in their game and the rest will follow."