So, Saracens have 7 in the squad. For the moment, let's assume they'll get £80k for each of those players, that's an addition £560k, which is 1 world class superstar, or probably 3-5 3rd choice players.
We may have 5 in the squad, but until recently, it's been pretty much just Joe and Elliott, so at best, we get £160k
If Sarries have regularly been getting an additional £400k more than us, that's about 6% of the salary cap (the cap was £6.5million in 2016/17 when we would likely have just had 2 in the squad - maybe 3 with Haskell)
Saracens still do an amazing balancing act given the number of top players they have, but an extra £400k does go some way to explaining how it's possible.