He added the minds of the team were "not right", claiming England were also "short of some quality players".
Alastair Cook's men arrived in Australia seeking to become the first England side to win four Ashes series in a row since 1890 following a 3-0 triumph over their oldest rivals in the summer.
Instead, they were
thrashed by 381 runs
in the first Test in Brisbane and suffered another hiding on a flat track in Adelaide.
England have only passed 200 once in four innings, their batsmen frequently contributing to their own downfalls. In fact, of England's 40 dismissals, 21 have come to catches on the leg side.
"The worst thing is that this performance was no different from Brisbane," added Boycott. "We are giving wickets away by pulling and hooking and getting out at fine leg and square leg.
"You can't win a Test match if you can't bat. If you keep making poor totals you are always under pressure.
The analyst: How England can save Ashes
"If you don't make decent scores you don't give your bowlers a chance to win either and that is the problem.
"We don't seem to have a mindset to stay in and make them bowl us out. We are playing cricket like a 50-over game - crash, bang, wallop and out. That won't win Test matches.
"You have got to make steady innings. When you get in later on, you can sometimes take the odd spinner on. But it is like chess - you can't win a chess game in the first few moves but you can sure as hell lose it."
England got to number one in the ICC Test rankings after beating Australia 3-1 down under and India 4-0 in 2011, but have since slipped to third behind South Africa and India.
With the team now one defeat away from a first Ashes series loss since 2006-07, Boycott believes England are in decline.
"They are like my side, Manchester United," he added ahead of the third Test in Perth, which starts on Friday. "I think the glory days have gone. I don't think they are there as a team. It is all beginning to unravel."
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