“Football is not 45 minutes, football is 95 minutes and the second half was totally different,” Southampton manager Ronald Koeman told BBC Sport.
“The first 20-25 minutes of the second half we lost control. When Carroll came in he changed the confidence of the West Ham team, because the first 45 minutes Southampton were by far the dominant team.
“We spoke at half-time about how they will give a reaction, they will bring in Carroll, which means they will play the long ball, they will fight for second balls, they will be more aggressive, and then you need to concentrate.
“If you play so well for 45 minutes and you get some very good chances you have to score more than one and we didn’t.”
Koeman also took to his own official twitter account to tell Saints fans “Disappointed final result! If you play so well during 45 min you have to score more than 1 goal! More mistakes in 2 half!