And just to add a personal note - a quantity for quality trade is a classic fantasy shark move and one I got badly burned by when I first started dynasty 15 years ago.
I traded Marvin Harrison and I got Tim Brown, Wayne Chrebet, James Stewart and someone else. I thought "wow, this is a great trade, I'm giving away one 1,000 yard WR and I'm getting 2, and a starting RB, pretty cool, eh?"
But of course Harrison went on to have a superlative career with multiple absurd 100+ catch seasons with Peyton whereas Brown, Chrebet, and Stewart were out of the league within a few years.
In fantasy there are tons of average players but very few superstars, which means that because of relative value and scarcity those superstars are worth their weight in gold.
I would even go as far as to suggest you never trade quality for quantity and if you by great fortune happen to have a superstar, only trade him if you've got a ridiculous surplus at that position or he's on the downside of his career.
Young, ascending players like Bell (even with his issues) I would pretty much never trade.