I very rarely see specialists used.  If it's anything like their use in SLB I presume that's because they're rarely brought in.  That said, does anybody think this guy could be moderately successful as a LHS at the Major League level someday?  Not a guy I had tabbed as a BLer, but always looking for a rosterable player when I can find one.

Hardball Dynasty – Fantasy Baseball Sim Games - Player Profile: Gerald Broxton

Seems like he could probably pitch in 100+ games if Sparky would bring him in regularly enough.  I'll probably only have 2 setup guys, so do you think he'd get enough appearances to throw 40 or 50 innings?  And how bad would he be?  The control and vR are bad, but the GB/FB is great and pitches are very solid, vL is decent.

Not worth a roster spot.  Low control, mediocre VR/P2.   As a LHS, he'll still face as many RHB and he'll walk too many.   Not something I want from a short reliever.  Especially one that might give me 30 IP.

He isn't good enough to get left handers out consistently.

Besides the fact that the guy you posted isn't that great... the sim doesn't seem to use LHS and RHS well. I once had a reliever with something like a 75/45 vL/vR and tried to make him a LHS and he faced more righties than lefties. I even tried an experiment once where I set all my relievers to either LHS or RHS and they still faced about 2/3 righties and 1/3 lefties.

They'll start with facing a lefty, usually, but don't come out after 1 batter.   You pretty much have to set them at 5/5 PC in order to accomplish what you want.    And he'll still face about 50/50.  And pitch 25-30 innings.

I think it was only something like 60/40 actually even starting against a lefty. I remember giving up on it pretty quickly though. I should probably try it with some minor leaguers for the whole season just to see what happens but I'm too lazy.

It doesn't seem like it matters which side people bat from due to splits.

The only case I can see making for a lefty specialist if you are playing a team who actually has very diverse lineups, and even then, you could only bring him in if you have a righty starter. The AI won't really help you out here so I see no real chance to use a lefty specialist except for a playoff when you are looking at every lineup every game.