Oakland A's announce Henderson Alvarez signing, designate Arnold Leon for assignment

The Oakland Athletics have officially announced an agreement with right-handed starting pitcher Henderson Alvarez. Alvarez will earn $4.25 million in 2016, with games started incentives of up to $1.6 million, according to SB Nation's Chris Cotillo. Alvarez has under five years of major league service time, and will remain under club control through 2017, his final arbitration season.

To clear space on the 40-man roster for Alvarez, the A's designated Arnold Leon for assignment. The club has ten days to waive, trade, or release Leon.

Details on Alvarez's incentives were published by Jon Heyman of CBS Sports:

Henderson Alvarez, $4.25M plus 100K for 12, 15 gs, 150K for 18 gs, 200K for 21 gs, 300 for 24 gs, 350 26 gs, 400 28 gs. #a's

— Jon Heyman (@JonHeymanCBS) December 29, 2015

Alvarez is recovering from mid-season shoulder surgery and was non-tendered by the Miami Marlins. He appears to generally be on the schedule outlined by Jeff Passan in a tweet last month that has him "on pace for [an] April return to games." On Alvarez's Instagram account, we can see him making towel throws about three weeks ago, throwing across the 50-foot width of a basketball court two weeks ago, and around 60 feet on a football field a week ago.

Nicknamed "The Entertainer", Alvarez brings a delightful eccentricity to the clubhouse. Joe Frisaro of MLB.com writes about what you can see on the field, the eephus he throws once per game,

and the old-timey windup on his first pitch:

Leon, 27, made his major league debut on April 22 last year. He made 19 relief appearances over 26 2/3 innings with a 4.39 ERA, striking out 19 and walking nine.