Looking at the most recent games of DRX during Split 1 and Playoffs, I noticed that Foxy9 has been consistently underperforming in nearly all games.
In their last 7 games (5 from split 1 and 2 from playoffs), Foxy9 went positive in just one of them (+3 against ZETA).
In the other 6 games he went:
-12 against PRX
-7 against RRQ
-1 against Talon
-9 against DFM
-10 against Talon (they won this game 13-8 and 13-4 btw)
-11 against GenG
Considering all this, getting rid of Stax after Split 1 seems like a pretty poor decision, especially since Stax and Foxy share a few agents in their pool (Breach, Kayo).
I know that Stax didn't want to igl anymore, but he is still a very solid player who consistently performs better than Foxy. Its also probably easiest to learn how to play Sentinel agents (the agents that Foxy is primarily playing)