Koplove, 32 years old, is hardly an up-and-comer. He has significant major league experience, mostly with the Diamondbacks. He is a quintessential AAAA reliever - too good for AAA, not quite good enough to stick in the majors. One look at the Tacoma staff says they could use a guy like Koplove, which in turn means the M's could use a little more depth.
It's hard to say much about Deybis Benitez. He is 22 years old, and is yet to log much playing time at any professional level. I've seen him listed as a shortstop and an outfielder, which leads me to believe he does not even have a well-defined defensive position (or that he is being transitioned to the outfield).
In the end, this is likely an extremely insignificant deal. Koplove may show up in September. Benitez probably will never reach the majors. If Koplove shows up at any point, now you know where he came from. More than anything, it is yet another example of how easy it is to acquire mediocre bullpen talent.