Brentford have fingers crossed the second player signed who spent time with Rochdale has better luck than the first.
Poor Hogan lasted a month of the season after joining Brentford in the summer before suffering anterior cruciate ligament damage that keeps him out for the next two months at least.
Manager Mark Warburton is hoping for better this time, and hinted his new player that has a contract with the Championship side until 2018, is very much one for the future.
He said: “We are delighted to secure another very talented young player. Jack is a player who has significant development potential left in him, and he fits the profile of what we look for when bringing a young player in to the club, who will benefit enormously from working and playing with our senior professionals.”
Besides Dale, O’Connell had loan spells at Rotherham and York City during the 2012/13 season.
He has played 38 League Two games for Dale alongside Hogan as Dale won promotion, making 45 appearances in all competitions.
He then went back to Rochdale for the first half of the current season and made 17 League One appearances before Warburton and Bees made their move.
The 20-year-old has represented England at U18 and U19 level making nine appearances in total.