The north-London club have been hit by injuries this season with the likes of Micky van de Ven and Cristian Romero continuing their return to action on Thursday night after both suffered long-term issues in December's 4-3 loss to Chelsea.
Spurs advanced to the quarter-finals of the Europa League on Thursday but they have struggled to balance European and domestic football, with the club sitting 13th in the Premier League.
"I'm telling you, the player attrition rate for teams in Europe is going to catch up with everyone," Postecoglou said when asked about the impact of European football on squads.
"I know people look at us, but ask any club this year that's in Europe; we've got a big fixture schedule and they've all got problems. Now, sometimes they're not as significant because it depends who they hit.
"With us, I think they've hit significant players which meant they've been even more exacerbated, but I think it's probably affected a lot of clubs that are in Europe this year - their league form."
Spurs face a Fulham side on Sunday who are among the handful of teams in the mix for European qualification, with Nottingham Forest occupying third.
The demands of playing three matches a week for clubs such as Spurs had aided their rivals' push up the table, according to Postecoglou.
"That's allowed very good football teams like Fulham and Bournemouth, and Brentford, and Brighton, and Forest, and Newcastle to ... yeah, it's pretty tight up there," he added.
"Particularly if they haven't had any sort of lengthy cup run then, yeah, it's a competitive league. But I don't think that's going to be any different from now on.
"For all clubs, the attrition rate is just going to increase if you're in Europe. You're going to find more and more clubs either going up the table or falling down, depending on how healthy they can keep their players."
Lucas Bergvall was instrumental in Spurs' 3-2 aggregate win over AZ Alkmaar on Thursday.
"He's worked hard at it. It's a big jump for him coming from the league he was at to the Premier League in one step," Postecoglou said about the 19-year-old, who joined from Swedish club Djurgardens in the summer.
"Usually people have a step in between, another league before the Premier League, but he made the step straight away.
"I think even visually you've seen how much he's grown in this eight or nine months since he's been with us.
"For us it's exciting. I still think his technical proficiency is his greatest asset, but he's added this to it now where he understands the physicality of the Premier League and it's exciting."
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