Aiden O'Brien has taken aim at former Sunderland boss Lee Johnson after describing his spell on Wearside as "absolutely abysmal." The former Black Cats striker left Wearside in January after a stop-start campaign.
The Republic of Ireland international played a key part in Sunderland's play-off push last season but found game time hard to come by this time round. O'Brien was one of the standout performers for the Black Cats in the Carabao Cup, scoring a hattrick against Blackpool only to be benched for the following league game.
O'Brien signed a short term deal with Portsmouth in an attempt to kick start his career once more after a difficult spell on Wearside. The forward was far from prolific in front of goal but chipped in with important goals last season.
