Paul Sturrock has threatened to drop players from Southend's squad after they slipped to a 2-0 defeat at Paolo Di Canio's Swindon.
Goals either side of half-time from substitute Jonathan Smith and Algerian striker Mehdi Kerrouche condemned Southend to a one-sided loss.
former Swindon boss Sturrock, who endured an unhappy return to the County Ground, said: "Some players will have played their last game for a very long time for Southend after that performance.
"It was very, very disappointing and sometimes you can win when eight players are on form and three perform badly, but here it was the other way around."
Sturrock added: "There's no thought process going on out there and that is why we have conceded four goals in our last two games.
"Swindon were hungrier and more professional and that is simply not acceptable."