The Padres traded left-hander Drew Pomeranz to the Red Sox in exchange for top prospect Anderson Espinoza, the team announced on Thursday night.

Pomeranz, 27, has this season pitched to a 2.47 ERA (161 ERA+) in 102 innings for the Padres. He just recently appeared in the All-Star Game at Petco Park. The No. 5 overall pick in 2010, Pomeranz has long been regarded as having front-line stuff but until this season health and performance had never intersected. He's under contract for $1.35 million this season and won't be eligible for free agency until after the 2018 season.

As for the Red Sox, they enter the second half ranking ninth in the AL in rotation ERA and also ninth in rotation FIP (Fielding Independent Pitching).

The Red Sox are taking a big step to fixing their rotation woes. USATSI

Espinoza, 18, ranked as the no. 15 overall prospect in the Baseball America midseason top-100 list. He's 5-8 with a 4.38 ERA and 72/27 K/BB ratio in 17 starts with Class A Greenville. The Red Sox have a lot of depth at the minor-league level, with Espinoza just one of three Boston prospects in the top 15 of the Baseball America list, which means they're well positioned to make a trade such as this one.

Here are six things to know about the trade:

1. This isn't Pomeranz's first good season

Since the start of the 2014 season, Pomeranz has pitched to a 2.84 ERA in 90 games, 36 of which have been starts. From 2011-13, Pomeranz had an ERA of 5.20 in 34 games, 30 of which were starts. Obviously, that's steady improvement and it probably has something to with the fact that Pomeranz now has a legit third pitch. Take a look at his Brooks Baseball pitch-usage chart vs. the opposite side ...

Brooks Baseball

As you can see, Pomeranz started throwing a cutter this season, and it has yielded good results for him. Gradually, he has started to favor it more and more over his inconsistent changeup. Pair that with his fastball and excellent curve, and you have a playable starter's repertoire.

2. Pomeranz is headed into a much tougher environment.

Not only is Pomeranz headed from the non-DH league to the DH league, he's also going from a run-suppressing home park to a much more hitter-friendly home venue. As well, he'll be paying semi-regular visits to hitter's havens in Baltimore, Toronto and the Bronx.

3. Pomeranz's health and durability remain concerns.

In the past, he has dealt with biceps, shoulder and hip problems. That, along with his work as a reliever, means that Pomeranz in 2016 has already set a career high in big-league innings (102 so far vs. a previous high of 96 2/3 with the Rockies in 2012).

Will his arm hold up and can he remain effective given that he's on pace to roughly double his previous high major-league workload? Throw in his time in the minors from 2012, and he's still under 150 innings for that season. As the innings mount in what will be a much tougher setting, all of this bears monitoring.

4. The Red Sox had a retread lefty who recently discovered effectiveness, but they let him walk.

Last year, Rich Hill enjoyed a 13-start run of dominance with the Red Sox, but Boston let Hill, now 36, depart via free agency. He went back to Oakland on a one-year, $6 million deal and he has continued pitching at a high level. Had Boston brought Hill back, they likely wouldn't be parting with one of their top prospects in exchange for Pomeranz.

5. Dave Dombrowski has helped restock the Padres' farm system.

Before last season, Padres GM A.J. Preller strip-mined his minor-league system for an ill-advised run at contention. Preller has since pivoted, and while he hasn't undone the damage, his deals with Boston have gone a long way toward doing just that.

Obviously, there's Espinoza, who immediately becomes the best prospect in the Padres organization. But don't forget about the November 2015 trade that sent closer Craig Kimbrel to Boston in exchange for four prospects: shortstop Javier Guerra, outfielder Manuel Margot, infielder Carlos Asuaje and right-hander Logan Allen. Here's what Preller said at the time:

Taken together, these are bold, win-now moves by Dombrowski and the Sox, but they paid dearly for a reliever and lefty who's just barely a known quantity.

6. That said, this potentially moves the needle for Boston.

Per the SportsLine Projection Model, here's how the deal for Pomeranz helps Boston ...

Red Sox
Projected wins % of winning AL East % of making playoffs
% winning World Series
Without Pomeranz
88.9 10.6%
55.4% 3.9%
With Pomeranz
91.7 23.4% 78.2% 6.3%
Difference +2.8 +12.8% 22.8% 2.4%

As you can see, Pomeranz improves their rest-of-season outlook by quite a lot, especially considering that we're more than halfway through the regular season. This says as much about Pomeranz as it does the bad innings he'll be bumping from the very thin Boston rotation. Cast in this light, it's easy to see why Dombrowski and company made this deal.