Only really once in the last 20-30 years have we sold a big player and used the money effectively to improve the rest of the team for a net gain, that was when we sold Keane and spent the money on Akinbiyi, Branch, Ndah, Oakes and Pollet. Otherwise we have a really bad track record at it so I'd rather we didn't.
1998 - sold Froggatt, funds not given to McGhee, Lee bought Flo and Niestroj when he took over
2000 - sold Akinbiyi, bought Taylor, Ketsbaia, Dinning, Butler, Roussel
2004 - loaned/sold Camara, bought Seol and Olofinjana
2006 - sold Lescott, didn't have the money to reinvest, Mick consigned to freebies and cheap lower league signings
2012 - sold Jarvis and Fletcher, bought Sako, Doumbia, Sigurdarson, Margreitter, Boukari
Before my time but arguably spending all the Steve Daley money on Andy Gray wasn't brilliant business either.
I'm not counting Olofinjana as the big lummox was only a big player in the sense that he was over 6 foot, we improved immediately just by selling him, let alone signing replacements.