yeah they have to pay that money and even more if the cut Sony. So they win by saving a little money and getting picks.
We win by just taking on his base salary, instead of paying someone say $500k more. Also there are no guarantees, if we had signed someone else there would have had to be some guarantees (most likely a signing bonus).
So we get tons of flexibility, we can cut him tomorrow if need be and sure we are out the picks but that is the ceiling of risk. Reward wise, if he performs and ends up being the best version of himself we have a solid RB at a cheap price for this year.
I also think New England does not make RBs look great, they have not had a dominant RB in who knows how long. So it is possible that Sony is a better RB on the Rams, but you cannot bank on that.
The real question remains then: would you spend $500k to get a 6th and 4th in one and two years down the road?