Soria has decent enough FIP, xFIP, and xERA numbers. His ERA is a bit inflated.
He is definitely lower on the totem pole and should not be a high leverage guy but he won't be in the playoffs unless Charlie wants to actually get fired. We'll see.
Yesterday was a big lead. It was fine to use him. Dude gave up a two run bomb and it was still a comfy win.
The pen is basically:
Closer - Romano
Reliables - Mayza, Cimber, Richards
Unreliables with promise - Pearson, Merryweather, Borucki
Unreliable with veteran savvy - Soria
Long man - Stripling
There are definitely certain situations where you would prefer Soria to any of "unreliables with promise". Borucki has lost the zone and Merryweather/Pearson have so little experience this year, any of the three are more liable than Soria to like, walk the bases loaded or f*** up so bad that it leads to a monstrous inning. Soria might give up some hits but to me he seems more likely to do the basic thing correctly (throw strikes, make the other team earn it).
If the reliables are not available who to go to in a 6-1 or 7-1 game? I see the case for Soria there.
If the reliables are not available and you need someone to come in with men on and get huge strikeouts, that should be the time to roll the dice on Merryweather or Pearson.
The wrong time to use Soria is when you need to get out of a tight spot. IMO.