I'd get rid of them both in a heartbeat, but it's just not as simple as that unfortunately.
Striker partnerships are just one of those things, they either click (Bellamy and Tevez) or end up shite (Torres and Keane). If ''new striker'' and Gabby don't click, and all we have is another new striker or the fonz to rely on there would potentially be a big detriment to the team in the wait of the partnership forming.
Whereas if you bring in a new lad and he struggles at the start you can bring on the old partner Carew then you are in a more comfortable position.
I'd take the risk, personally, but MON isn't a big risk taker. Time will tell.