The Cubs bullpen

Aroldis Chapman may have the fastest pitch in
major league history. 

A big deal went down Monday: The Yankees shipped fireballing closer Aroldis Chapman to the Cubs for a rather impressive package of prospects. I don't much care for what we know of Chapman the human being, and this piece from the Chicago Tribune's David Haugh defines the uneasiness that should accompany rooting for Chapman. (He only details one incident, but there have been others.)

But as far as the Cubs are concerned, Chapman really only has to behave himself for three months or so. Then he becomes a free agent. The Cubs are willing to overlook his character flaws in pursuit of their first World Series title since 1908 and their first World Series appearance since 1945.

But then there's this:

The Cubs are 55-1 going into the 9th with lead, 53-1 going into 8th, 53-5 into 7th.  The upside for *any* reliever add is limited.

— Dan Szymborski (@DSzymborski) July 25, 2016

The Cubs have fallen off their early-season pace not because of its lack of stars in the bullpen but for other reasons. Example: Ace Jake Arrieta allowed four runs in six innings Monday night; it was the fourth time in five starts he's allowed that many runs. His ERA has risen from 1.74 to 2.76 in that span.

Still, it's the bullpen that the Cubs are aiming to beef up. Chapman is the second lefty reliever the Cubs have traded for -- they got Mike Montgomery from the Mariners for a couple of prospects last week.

And Old Friend Joe Nathan, back from another Tommy John surgery, made his first appearance of the year Sunday and struck out the side against Milwaukee. Nothing's certain about Nathan, of course; he's 41 and there's a lot of mileage on his arm. But if he is sound again ... well, he and Chapman and Hector Rondon (1.95 ERA with 18 saves) look like a pretty darn impressive crew for the late innings.

If Nathan is sound. If Chapman behaves himself, If, if, if.