England face India in Jaipur on Sunday in their Champions Trophy opener but are without Marcus Trescothick, Michael Vaughan, Ashley Giles and Simon Jones.
"We don't have the quality reserves to shore up the better players being injured," Boycott told the BBC.
"The reserves do the best they can but it does lessen the team's quality when you have too many fill-in players."
England reached the Champions Trophy final when they hosted the event in 2004 but since then have won only 16 of their 43 one-day games.
This summer they were thrashed 5-0 by Sri Lanka before coming from 2-0 down to draw 2-2 with Pakistan.
Newcomers like Jamie Dalrymple and Michael Yardy have been brought in to the squad to cover the absence of key players but Boycott believes they are not long-term answers.
"We're without so many good cricketers and people are being moved around to fill gaps," said Boycott.
"We don't know if England are a poor one-day side or quite a good one when all the players are fit.
"If we've got everybody fit, particularly Vaughan for his captaincy, we might be a lot better and be able to surprise ourselves that we're quite a decent one-day side."
Boycott believes that moving skipper Andrew Flintoff up to either open the batting or go in at number three could pay off.
"I don't have a problem with that because there's only two people out on the boundary, it's usually third man and fine leg, and he's a four-ball hitter anyhow," he explained.
"I think people have to play their natural game. It is his natural game to play shots. When he times the ball, it goes twice as quick as when someone like me times it because he's a big lad and it's difficult for the in-fielders to stop it."