==== 2011–12 season ====
On 22 November he joined [[Millwall F.C.|Millwall]] on a one month loan deal.ref He was assigned the squad number 27 and made his debut four days later, helping Millwall keep a clean sheet against [[Crystal Palace F.C.|Crystal Palace]].ref He made six league appearances before his loan spell ended in December with a 1–0 win against [[Portsmouth F.C.|Portsmouth]] on 26 December being his last game.ref He returned to Villa and made his first appearance of the season coming on as a late sub for [[Richard Dunne]] against [[Manchester City F.C.|Manchester City]] on 12 February.ref==== 2012–13 season ====
During the 2012–13 season, Baker established himself as a centre back with great aerial ability. Due to an injury to [[Ron Vlaar]], Baker was partnered with fellow Academy Graduate [[Ciaran Clark]] and impressed during a difficult spell where Villa conceded lots of goals. On occasion he also played at left back in the absence of . On 9 March, Baker scored a horrendous own goal, swinging his right foot at the ball, missing it completely and it ricocheted in off his standing left foot.ref However after the game, Baker was praised for putting this behind him and having another outstanding game, before being replaced by Bennett in the 80th minute. In May 2013 Baker signed a new three-year deal with Ason Villa which would keep him there until 2016.