Fraser expects to make a number of new additions to the squad.
Middlesex managing director of cricket Angus Fraser says he expects a marked improvement from the team next year.
The former England and Middlesex bowler took charge last winter but has watched the side struggle in the County Championship this year.
Fraser told BBC London 94.9: "It's been a tough summer and we've not performed as well as we'd have liked.
"Have we got poor players? No. Have we got a poor side? I don't believe so. Have we underperformed? Yes."
Fraser added: "The challenge for me and the coaching staff is to make sure the players get more out of themselves and we get more out of them next year.
"There were some encouraging signs. To see the likes of Sam Robson, Adam London, John Simpson, Steven Finn and Gareth Berg all make progress is a good sign for the future, but you don't want to be rattling around the bottom of the second division, which is what we've been doing for most of this summer."
Next season, Middlesex will be without Alan Richardson, who has signed for Worcestershire, while the club has decided not to offer new deals to Chris Silverwood and overseas player Murali Kartik.
"There are holes to fill. We are speaking to people and hopefully some of the people that we are speaking to will sign on the dotted line and we'll have a slightly different squad next year," Fraser said.
"Murali Kartik has bowled very, very well for us this year, and has been a good performer over the last three years, but I think some sides see our tactics before we hit the M25 - you turn up with two cagey, old, very good spinners and they produce pitches accordingly.
There are holes to fill. We are speaking to people and hopefully some of the people that we are speaking to will sign on the dotted line
Angus Fraser
"Therefore you're either playing with a slightly compromised side or leaving one of your high-profile players out.
"So we'll be looking at an overseas fast bowler next year, another fast bowler to strengthen our fast bowling resources, a young left-arm spinner and a batsman to add some experience to our youthful batting order."
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