The top teams in the National League and American League were involved in a notable deal Friday, with the Baltimore Orioles sending outfielder Austin Hays to the Philadelphia Phillies in exchange for relief pitcher Seranthony Domínguez and outfielder Cristian Pache.

After an All-Star season last year, Hays is struggling with a .255 average and .711 OPS with 13 doubles this season. But as a right-handed batter, he could fit nicely in a center-field platoon with Brandon Marsh in Philadelphia. Against left-handed pitching this season, Hays is batting .328 with an .894 OPS.

For Baltimore, Domínguez should fortify a bullpen that is in the middle of the AL with a 3.75 ERA. The right-hander has 40 strikeouts in 36 innings. Pache provides outfield depth, especially defensively. At the plate, he's slogging through a .202 batting average and .557 OPS in 118 plate appearances.

The Orioles continued their aggression in the trade market later Friday, dealing for Tampa Bay starting pitcher Zach Eflin, according to ESPN's Jeff Passan.

Why’d the Phillies do this?

They needed an outfielder who hits lefties. Hays, who has a career .791 OPS against southpaws, is exactly that. Bearded wetman Brandon Marsh, a lefty hitter, is still a difference-maker against righty arms. But the hirsute slugger struggles against same-sided pitching. The previous two Octobers, the Phillies paired him up with Matt Vierling and then Pache.

Hays offers a bit more offensive punch. He’ll start against the best left-handed pitchers in the NL, such as Atlanta’s Max Fried and Chris Sale. A right-handed-hitting outfielder was the biggest task on the trade deadline to-do list of Phillies president of baseball operations Dave Dombrowski. With this swap, he checks that box early — and without trading any prospects. — Jake Mintz

Why’d the O’s do this?

They have too many outfielders and need bullpen help. Domínguez will help Baltimore’s undermanned relief crew immediately. The righty has been a high-leverage option for Phils manager Rob Thomson the past two autumns but fell down the pecking order this year with a string of inconsistency. The O’s will hope to tweak a thing or two, as they’ve done before with bullpen arms such as Yennier Cano, and have Domínguez hucking in big moments come October.

Pache fits much better on the Orioles’ roster than Hays did, mostly because he can play center field. Cedric Mullins, a lefty bat, is still the every-day guy, but Pache should see time against left-handed pitching. He’s a better defensive option than both Hays and Colton Cowser, who has been Baltimore’s secondary option out there this year.

The O’s certainly aren’t finished at this deadline. Acquiring a starting pitcher or two is a must for the Birds. But this minor deal helps them get better now without giving up too much. That said, it will be interesting to see how the loss of Hays, one of the team’s longest-tenured players, impacts the clubhouse.

Overall, this is what a trade should be, what trades looked like back in the day — one big leaguer in exchange for two big leaguers, a pair of contending teams doing some wheeling and dealing, trying to get better at the margins. None of that prospect-you’ve-never-heard-of-for-veteran rubbish. Good job. — Mintz

Red Sox bring back James Paxton

Also Friday, after being designated for assignment by the Los Angeles Dodgers, pitcher James Paxton finds himself on his way to the Boston Red Sox.

Paxton, 35, is headed to Boston in exchange for minor-league infielder Moises Bolivar, ESPN's Jeff Passan reports. Paxton had an 8-2 record this season for the Dodgers, but with a 4.48 ERA and a National League-leading 48 walks (tied with the Cincinnati Reds' Hunter Greene) in 89 1/3 innings.

The veteran left-hander returns to the Red Sox after pitching for them last season. In 19 starts, he compiled a 4.50 ERA and 7-5 record with 101 strikeouts in 96 innings. He'll provide depth for a starting rotation led by All-Star Tanner Houck that could now go seven arms deep.

Bolivar is an extremely young prospect playing for the Red Sox's Dominican League club at 17 years old. He's batting .270 with a .787 OPS, six doubles, three home runs and 19 RBI in 132 plate appearances.

The Red Sox are currently in third in the AL East at 54-47, 6.5 games behind the Baltimore Orioles. They're one game out of the AL's final wild-card playoff spot.