Patrick Newbman of NPB Tracker (via MLB Trade Rumors) says that the Pirates have signed Ryota Igarashi to a "split contract," which I think means a minor league deal that would pay him differently if he makes the big league club (think Jose Veras last year). Igarashi's worked 69 innings out of the Mets' bullpen over the last two seasons and before that was a reliever with Yakult in NPB's Pacific League.
He doesn't have much to show for his time with the Mets, but he throws pretty hard (his fastball averages around 92-94) and his strikeout numbers with the Mets were (67 in 69 innings). He struggled with his control in New York quite a bit, which really hurt his overall numbers, but that seems like something maybe the Pirates can help him with. Certainly it won't hurt to have another potential bullpen arm in camp.
And of course, you can probably guess that I like the signing because I think the Pirates need to be branching out into the Far East market more and while Igarashi isn't a star by any means, he is another Japanese player they can put on the roster to help towards making the Pirates a more viable destination for Japanese players. Hopefully, this will work out better than the Akinori Iwamura experience.
Pirates would be dumb to trade a Jed Lowrie type for bullpen help, but would a team with the Red Sox budget ever actually use Lowrie as an everyday player?
Like you say, there ain't nothin' wrong with having a lot of live arms in camp on the cheap; there are worse ways to build a bullpen (exchanging Jed Lowrie for Mark Melancon comes to mind.)