Victor Wanyama, who has been linked with Arsenal, was labelled "stupid" by Koeman after being sent off for two fouls against Norwich while Sadio Mane was dropped for the game for a breach of club discipline.
The Dutchman also hit out at the Senegal star for being late to a team meeting and it fueled speculation the pair could be sold with Manchester United and Chelsea said to be interested in Mane, as reported by the likes of the Daily Star.
'They can't keep doing this'
But legendary striker Shearer, who scored 313 goals in 622 career games for club and country including 28 for Southampton before he was sold to Blackburn Rovers, told Match of the Day the club cannot continue with its current transfer policy.
"They've got big decisions to make Southampton, there's obviously transfer speculation with the two of them, Mane and Wanyama," Shearer said on MOTD.
"(But) you can't keep on selling your best players and recruiting well it's a difficult job (to) keep recruiting."
Shearer is referring to the way Southampton have conducted their business in the last few years.
Recruitment not just down to luck
After establishing themselves in the Premier League the club looked to have pressed the self destruct button when they sold their best players like Rickie Lambert, Adam Lallana, Luke Shaw and Dejan Lovren as well as letting Mauricio Pochettino join Tottenham Hotspur.
The Saints were tipped by most to be relegated in the wake of the fire sale.
But they were the surprise package of last season challenging at the top end of the league and eventually qualifying for Europe with Koeman bringing in players many felt were as good as if not better than those sold in Graziano Pelle, Shane Long, Mane, Fraser Forster and Dusan Tadic.
Shearer is right to sound a word of caution to his old club as their luck could run out on the transfer front.
But the recruitment process at Southampton is obviously up there with the best in the league and there is not reason to think the club could not replace the likes of Mane and Wanyama if they are sold this window.