Loewen, 27, hit 17 home runs last year for the Blue Jays' Triple-A Las Vegas affiliate in the hitter-friendly Pacific Coast League, batting .306 with a .508 slugging percentage in 134 games.
A former blue-chip left-handed pitching prospect with mid-90s velocity, Loewen was the fourth overall pick in the 2002 First-Year Player Draft, first cracking the Majors as a 22-year-old with the Orioles four years later. But significant shoulder and elbow troubles led to massive control issues, ultimately forcing him to give up pitching altogether.
Reinventing himself as a power-hitting outfielder, Loewen spent three more seasons in the Minors before reaching the Majors again this September.
"To think about how far that guy has come to get back to this level is amazing," longtime Minor League teammate David Cooper said in September. "It's unreal. I remember when he first made the transition, and it's night and day. It's amazing how quickly he's picked up hitting."
Loewen's transformation is similar to that of another free-agent outfielder in whom the Mets have shown interest, Rick Ankiel, who has established himself as a serviceable reserve since converting from a star pitching prospect early last decade.
If Loewen can hit in the Major Leagues with the same consistency that he did in the Minors, the Mets may have found a replacement for left-handed reserve outfielder Willie Harris -- though re-signing the veteran Harris remains a consideration. Barring something unforeseen, the Mets plan to proceed with a starting outfield of Jason Bay, Angel Pagan and Lucas Duda next season.
Though Loewen's deal offers no guarantees of cracking the Major Leagues, he should receive a long look in camp with little more to prove in the Minors.
Harris and Scott Hairston, the club's two primary reserve outfielders from last season, are both free agents, as is utility man Nick Evans. Backup center fielder Jason Pridie was also a free agent before signing with the A's last week.