The Northern Ireland international, 25, underwent an operation to treat a knee problem last year and is at last available again for selection.
’Well boss Alexander said: “He’s not kicked a ball for me since I’ve been here in competitive games.
"He had half a game on Saturday which was brilliant and got through it really well, worked exceptionally hard.
"But we just have to remind ourselves that he’s been out for a considerable amount of time.
"But certainly when he’s fully fit that will be a new player for me without a shadow of a doubt because I didn’t have him available from January onwards and there will be other players like that.
"Liam Grimshaw, when he comes back in. I had him for my first game and he’s been missing since then so that’s been difficult.
"Bevis Mugabi is still rehabing from his shoulder operation so he hasn’t taken part in pre-season but when he comes back it will be like a new player again for myself because he missed the last part of last season.
"These are big players for us.
"We haven’t got a squad with the luxury of having 20 senior players.
"These players are vitally important to the success of Motherwell so we have to get them back into the fold as quickly as possibly but as safely as possible having been out for a long time.”
Alexander said there were “two or three candidates” for the role of club captain in the upcoming 2021-22 season.