The main component here is Profar going to San Diego. An interesting side note: Padres general manager A.J. Preller was the Rangers’ assistant general manager when Profar was coming up through the system, so it’s a bit of a reunion. 
As for the A’s return, Allen appeared in 34 games as a rookie last season for the Padres. The 25-year-old hit .215/.282/.277. In 67 games for Triple-A El Paso, Allen hit .330/.379/.663 with 21 homers, so there is possibly some untapped upside in the stick, even if those numbers came in the hitter-friendly Pacific Coast League.  Expect Preller to remain busy this offseason. The Padres haven’t had a winning season since 2010 and have missed the playoffs every year since 2006. His seat is likely pretty hot, so they need a breakthrough season sooner than later.
The Padres’ infield now seems set. Eric Hosmer at first, Manny Machado at third and Fernando Tatis at shortstop were already in place. Urias was sent to Milwaukee with starting pitcher Eric Lauer for outfielder Trent Grisham and starting pitcher Zach Davies last week. Ian Kinsler is still around, but he’s past the point of being an everyday player, so that’s where this Profar move comes into play.  The move fills the Padres’ void that was left at second base after Luis Urias was dealt to the Brewers last week. Profar has experience defensively all over the diamond, but second base is where he’s spent the most time. 
The Padres have acquired infielder Jurickson Profar from the Athletics, the team announced Monday. In return, the A’s get catcher Austin Allen and a player to be named later. Profar has been rumored to be a trade candidate for the past few weeks as the A’s are looking to reduce payroll after their second straight Wild Card Game loss. Reliever Blake Treinen might also be on the move soon. Oakland traded Profar just hours ahead of Monday night’s non-tender deadline.
Profar, 26, hit .218/.301.410 (90 OPS+) with 24 doubles, 20 homers, 67 RBI, 65 runs and nine steals last season with 0.8 WAR for the A’s. His breakout season came in 2018 with the Rangers. The A’s acquired him via trade last December as part of a three-way trade.