Realistically moving forward we have one roster slot for one of Cimber, Green, or Pop. If they decide to upgrade the pen it would likely be an elite arm, preferably a lefty to share the load with Mayza.
We could also upgrade the rotation, ideally with at least a #3 level SP. This would allow us to put Kikuchi in the pen during the playoffs where he would be a weapon.
Realistically, the best chance we'll have to upgrade is a lefty mashing outfielder which should be way cheaper than an elite RP or SP. I would sit one or both of Varsho/Kiermaier against LHP until the team starts hitting. Their defence is elite but it doesn't matter when we're getting shut out.
Guys like Tommy Pham, Rob Refsneyder, or maybe a guy like Victor Robles really shouldn't break the bank.