The skipper was critical of his team in their fielding, bowling and batting but still felt that his side should have chased down 244 to win at the Kensington Oval.
Instead they were bowled out for 169 by Ireland in the 42nd over.
"The way we played today we deserved to lose," Bashar told reporters. "It was one of those days when nothing went right for us. We fielded pretty ordinary, we bowled poorly and then chasing, we lost too many early wickets.
"It's very much frustrating for me," he added. "We've done a very good job in this World Cup so far by beating two big teams (India and South Africa).
"One day we look brilliant and the next we are ordinary. We need to be more consistent."
His comment referred to the way Bangladesh beat India in the group stage to oust the 1983 winners and then South Africa eight days ago when the Proteas were still ranked one in the world.
Bangladesh have been a fully-fledged test outfit since 2000 and have beaten Pakistan and defending champions Australia in previous years, but the defeat to World Cup debutants Ireland was one of their most embarrassing reverses.
"It looks like we are going to be number eight (in the Super Eights) after this match and we had hoped we would be sixth or seventh," Bashar said. "I must give credit to Ireland though. They played very well and put us under pressure."
Bangladesh are bottom of the Super Eights table on two points. They trail Ireland on net run rate.
Bangladesh's last match of the tournament is against hosts West Indies on Thursday in Barbados.
The seven-week tournament, the first in the Caribbean, started with 16 nations and was whittled down to eight for the second-stage Super Eights.
The final will be in Bridgetown, Barbados on April 28.
