Now that the discussion about Morse is out of the way, we can take a look at who the Mariners got in return.
Xavier Avery is a left-handed outfielder in the Orioles organization. He's played all over the outfield, and is 6'0'', 190 lbs. He's considered to be an excellent athlete and a good defender with plus speed.
Avery got a taste of the bigs last year. After a hot start in AAA in 2012, the Orioles called Avery up in May, where he continued to hit for a few weeks. Then, he fell off, and was eventually optioned back down. His year fell apart after that, and he ended up with a .686 OPS, which is only slightly better than the .223/.305/.340 line he compiled across 107 MLB plate appearances with Baltimore.
This year has been even worse for Avery, as he found himself back down to AA to start the season. He hit reasonably well at that level and earned his way up to AAA, where he's been terrible. Avery has a 77 wRC+. He's hit for no power (.075 ISO), and while he has some speed (17 SB), he really hasn't been on base enough for it to matter.
John Sickels wrote about Avery in his 2013 prospect book, and here's what he had to say.
Xavier Avery remains more athlete than baseball player, though he's made some progress. He's tapping into his power a little more often, and he's doing a slightly better job controlling the strike zone. He is using his speed better on the bases, and he's developed into a good defensive outfielder. He can bunt. But overall, his offense remains disappointing, hampered by problems with contact that will preclude him from being a regular outfielder if they aren't resolved. His other skills could keep him employed as a reserve for some time, and he's still reasonably young at age 23. Grade C.
Sickels ranked Avery as the #12 prospect in the Orioles system before the season began, and checked in on his rankings in July.
12) Xavier Avery, OF, Grade C+: Borderline C. .300/.391/.406 with 12 steals for Bowie in 39 games, .216/.291/.284 with 12 steals for Norfolk in 55 games. No change here: really good tools, but bat is shaky against good pitching. Profiles as a reserve for me.
Avery seems to be that classic toolsy player that looks better than he hits, much like Francisco Martinez. He's either going to put it all together and be a semi-valuable 4th outfielder or he'll toil in the minors indefinitely. In all likelihood, it's going to be the latter. He's declining as a hitter, and no amount of athleticism is going to salvage a career for Avery until the bat comes around at least somewhat.
This is the warm body most expected the Mariners to get in return for Morse. At least Avery has a small chance to carve out a major league career. He's already made it up once, and if the results ever catch up to the athleticism, there could be something here, but probably not. Avery is no more the future 4th outfielder of the Mariners than Trayvon Robinson was. Besides, Robinson actually hit in the minors.