Mariners' latest trade fills a big need in the most boring way possible

It was only a couple days ago that Seattle Mariners president of baseball operations Jerry Dipoto was openly talking about wanting to be "aggressive" on the bullpen market, and the big move that this would entail may yet happen before the trade deadline passes on Thursday.

In the meantime, the Mariners have pulled off a generally unspectacular, yet highly intriguing trade for Pittsburgh Pirates left-hander Caleb Ferguson.

The deal was first reported by Ken Rosenthal of The Athletic, with Adam Jude of The Seattle Times subsequently reporting that right-handed prospect Jeter Martinez is the return for Pittsburgh. Martinez had ranked as Seattle's No. 13 prospect for MLB Pipeline.

Caleb Ferguson is the second lefty the Mariners needed in their bullpen

The 29-year-old Ferguson has been in the majors for seven years, though he's one of those guys who feels like he's been around forever. It's probably because everything about him screams "Standard-issue lefty reliever!"

Ferguson, who's on a one-year deal that pays out $3 million, throws from a three-quarter arm slot and works off a four-seamer with basically average velocity, with a cutter, sinker, and slurve to keep batters off balance. He is primarily useful in platoon matchups, and especially this year as he's held lefty batters to a .439 OPS.

Yet there's also a bit more to Ferguson than meets the eye. Increased reliance on his sinker has helped make him near impossible to square up this season, and not just in the sense that his ground-ball rate is a touch above 50 percent. His exit velocity and hard-hit rate are both in the 100th percentile.

The catch is that he's fanning only 19.3 percent of the batters he's facing, which means he isn't a rising tide that will lift all boats in a Mariners bullpen that is short on swing-and-miss stuff. But that is fine, as manager Dan Wilson won't need to rely on Ferguson as his primary southpaw.

Indeed, we just wrote about how the Mariners needed a second lefty who could free up Gabe Speier to work in more high-leverage spots. Ferguson is perfect for the role, especially if it results in him getting critical mid-game outs against tough lefties (i.e., Riley Greene, Cody Bellinger, Roman Anthony) in the playoffs.

Meanwhile, the Mariners may yet have a bigger move up their sleeve. Also on their radar is Minnesota Twins right-hander Jhoan Duran, according to Joel Sherman of the New York Post. It was just yesterday that we tagged the flamethrowing righty as the best possible bullpen target for Dipoto.

That's a crowded race, though, and the clock is ticking. The deadline will come and go in just about 24 hours at 3 p.m. PT on Thursday.