Mallinder’s men were beaten 29-24 in the Aviva Premiership play-off semi-final at Franklin’s Gardens.
Their chances of victory were hampered by first-half injuries to Ahsee Tuala, Alex Corbisiero and James Wilson.
Saracens scored while Tuala was down and Wilson’s withdrawal at half-time left Saints needing to play wing Ken Pisi at full-back and centre Tom Stephenson on the wing.
But Mallinder said: “It’s not good when you lose two full-backs and your prop early on.
“We can’t blame injuries. It’s not ideal, but we won’t blame injuries.”
Saints were in the game with 18 minutes to go, trailing by five points.
But Owen Farrell, who racked up 19 points, put the tie beyond them with a late penalty.
And Mallinder said: “It’s all about small margins and we just didn’t get enough of those small bits right.
“In the first half we were perhaps a little too attacking from deep and what we needed to do was stick the ball back to them and make them turn.
“At the breakdown they were physical and the Vunipolas (Mako and Billy), when they get over the ball, their stomachs are touching the ground already.
“It’s near impossible to move them.”