I don't think JBarnes should be used again except in a mop up situation or long relief when behind big early. I've not been as down on him as many others have been, but he's become less effective 2d half and especially lately. More importantly, even if he was his typical slightly over 4 ERA, hard throwing, mostly ok for a low leverage role self like he was for the first 4 months or so, throwing him in situations like man on 2d, no outs, tied game, 1 run loses it (like extra innings last night) really would do next to nothing even if it works out OK. Barnes is not under team control for next year and is pretty old (34+, 35 next April). There's guys like Brzykcy and even Rainey who could contribute going forward (under team control) and have been pitching pretty well that Davey is reluctant to use who should be given a shot ahead of Barnes in game on the line situations.
Last night, I could understand why Finnegan wasn't in, and both Law and Ferrer have worked a lot lately. Similarly, Salazar had pitched 2 out of the prior 3 days, so I get why he wasn't turned to. Still, even if they failed, there's a lot more to be gained by exposing Rainey and Brzykcy to start the 10th than JBarnes.
Ranking the righties right now, in order of who should be used in the highest leverage, it's probably:
Finnegan
Law
Salazar
Rainey
Bzryckcy
Barnes
Barnes now should probably be the #9 guy in the pen.