Moreno, a five-year veteran, had his best season in 2013 when he rushed for 1,038 yards, caught 60 passes and scored 13 touchdowns playing with Peyton Manning and the Denver Broncos. He ranked fifth in the NFL with 1,586 yards from scrimmage, and tied for fourth with 10 rushing touchdowns.
Montee Ball, a rookie last year, made Moreno expendable in Denver.
Lamar Miller and Daniel Thomas were the Dolphins' primary ball carriers last season, and both remain on the roster. Moreno has a career average of 4.1 yards per carry, compared to 4.2 for Miller and 3.6 for Thomas.
The Dolphins' offensive line has been a big reason for their sputtering ground game. The unit also gave up a franchise-record 58 sacks and was rocked by the team's bullying scandal last year.
Center Mike Pouncey is the lone holdover in the line, and while the Dolphins added left tackle Branden Albert, they're still shopping for upgrades at guard and right tackle.
Denver made Moreno the 12th overall pick in the 2009 draft after he played at Georgia. He has career rushing totals of 3,468 yards and 26 touchdowns.
Moreno became a social media sensation he cried during the national anthem before a game in December. He has been slowed by injuries and has played in all 16 games just twice in his career.
AP NFL website: www.pro32.ap.org and http://twitter.com/AP-NFL