Kenny Jackett admitted the pressure might be getting to his Swansea players after their promotion push suffered another savage blow with their second defeat of the week.
Swansea had already blown two opportunities to go top of League Two this month when they were held to a draw against Southend before suffering a midweek defeat at Mansfield.
And their miserable February form continued when they produced another dismal display on a filthy afternoon in east London.
Jackett's side were torn apart as first half goals from Andy Scott and Daryl McMahon gave mid-table Orient a deserved 2-0 lead going into the break.
Worse followed for Swansea after the interval when Matthew Lockwood made it 3-0 from the penalty spot after Willy Gueret had brought down McMahon inside the area.
New signing Lee Thorpe pulled a late goal back for the visitors, but Swansea, making it three games without a win for the first time this season, scarcely deserved to take anything from the match.
Jackett pointed out his side forced more shots than Orient, but that was cold comfort for the 530 travelling fans who watched their team get totally out-fought in the swirling wind and rain.
And Jackett admitted: "Pressure is there all the time for players, and perhaps it is getting to them a little bit.
"It was a disappointing result and a disappointing performance. We were easy to penetrate and we didn't compete well enough. The people we have are capable of playing much better.
"To lose away twice in a week is very disappointing.
"But, as we come to a crucial stage of the season, I'm sure we'll bounce back from what has been a bad week for Swansea.
"I certainly hope we can respond positively to going three games without a win when we play Grimsby next weekend."
Jackett had made two changes to the side that slumped to the 1-0 defeat at Mansfield.
After a successful Wales debut in midweek, Sam Ricketts took Garry Monk's place in the Swansea rearguard.
The Swans boss was forced to rejig his back line again with Monk starting a three-game ban for collecting his third red card of the season at Field Mill.
The players' first-half efforts were hampered by the awful weather, but Orient defied the conditions to play better football.
Martin Ling's side were menacing on the break, serving warning of things to come as early as the ninth minute when Justin Miller's cross found Lee Steele loitering in the penalty area. Luckily for Swansea, Alan Tate made a vital block.
Minutes later, Gueret showed good composure to gather a well-struck effort from Scott.
But the Orient midfielder had better luck in the 15th minute when he rifled in a shot from the left-hand side of the box after Steele had taken advantage of dithering in the Swans defence.
At the other end, Swansea were frustrated as Izzy Iriekpen shot straight at the keeper from 10 yards before Harrison held a Lee Trundle free-kick.
So on top were Orient that it was no surprise when McMahon put them 2-0 up, the central midfielder driving a shot into the bottom of the net from an acute angle after racing onto Steele's pass.
Swansea had several chances to edge back into the game, the best chance came in first-half stoppage time when Trundle had time and space on the edge of the six-yard area, but the Scouser only succeeded in drawing a fine stop from Harrison.
Moments earlier Gueret had pulled off a magnificent one-handed save to prevent McMahon beating him a second time with a clever long-range lob.
Eight minutes after the break, however, Gueret was more villain than hero when he brought down McMahon inside the area and Matthew Lockwood buried the resulting spot-kick to increase Swansea's misery.
Trundle summed up the increasingly desperate nature of Swansea's approach when he was booked for diving in the Orient area in an attempt to win a penalty.
But Jackett's men managed to pull a goal back eight minutes before the end when Thorpe making his first Swans appearance since completing a free transfer from Bristol Rovers, drove a low shot under Harrison after picking up a short pass from Andy Robinson.
"If one of the many chances we had in the first-half had gone in, that might have changed the course of the game," lamented Jackett.
"But I can't have any complaints with the result. We've got to make sure we fight back from this."
REPORT: WALES ON SUNDAY