An off-spinning all-rounder, Middlebrook represented Yorkshire at every age level from under-11 upwards before he made his first-class debut for the senior side in 1998.
Though he struggled to hold down a place in the side, he impressed sufficiently against Essex in 2001 - taking three wickets and hitting 84 - to earn a move to Chelmsford the following season.
Middlebrook was the only Essex bowler to take 50 wickets in 2003, while he underlined his prowess with the bat courtesy of a maiden first-class century against Cambridge UCCE in 2004, a season that also saw him hit 115 against Somerset.
His 18 wickets helped Essex win the totesport League in 2005, and he was the county’s most economical bowler during the Twenty20 Cup campaign.
Though his 32 championship victims in 2006 came at a cost of almost 50 apiece, he formed part of the side that won the NatWest Pro40 title.
Middlebrook was the only Essex player to feature in every championship game in 2007 - he averaged almost 32 with the bat and took 24 wickets - and he proved himself a more than useful performer the following season with 31 wickets.
However, his time at Essex came to an end at the conclusion of the 2009 season after he was not offered a new deal and duly released by the county.