I would do this trade if I where you. Here is how you have to think about this with your 2RB, 2WR, 1FLEX format. If you don't make the trade you are starting:
AP, Lynch, Jennings, Marshall, Bowe
If you do make the trade your starting:
AP, Lynch, Benson, Marshall, Bowe
So its really a straight up trade Benson for Jennings
Benson has averaged 14 FF points a game and I don't think it is a stretch AT ALL to think that he will continue on that pace. In fact I wouldn't be shocked if he exceeds that slightly.
Jennings is averaging 7.5 FF points a game and will likely get a lot better, but 14 FF points better. This trade gives you more base value and better upside in your starting lineup.
Help with mine:viewtopic.php?t=454637