Boruc was never Koeman's first choice. He was loaned out in Koeman first summer and did not play a league game for Koeman.
Koeman and Forster's first season 2014/15 saw Saints only concede 33 goals, only Champions Chelsea conceded less (32 goals). People will probably say it was due to the players in defence and midfield, but for Forster to have the 2nd fewest goals conceded in the league he must have done something right that season! You don't only concede 33 PL goals with a good defence and midfield... the keeper is doing something right as well.
Timeline
- Nigel Adkins signed Boruc in August 2012
- the bottle incident happended in October 2012 when Adkins was manager
- Adkins then dropped him until January 2013
- Pochettino joined in January 2013
- Boruc was the regular keeper for Pochettino
- Koeman joined Saints in June 2014, Forster joined in August 2014