Mabbutt feels there's no point keeping the Chelsea target against his will.
He told talkSPORT: “The way that last season went and the way the team performed in the Champions League it attracted a lot of attention to the club and the players globally.
“The main thing is that missing out on the top four last year the players got a taste of Champions League football and when you’re getting big offers coming in with the opportunity of playing in the Champions League and there is always a risk of this happening.
“It’s not a surprise we all knew it was going to happen. We just hoped we could hold on to the players for another season at least and get back into the top four.
“We’ve got to look to the future, if he wants to go there is no point holding back an unhappy player, you’ve got to use that money and build.”