The 74-run defeat sent Bangladesh to the foot of the table with just one match left against West Indies here on Thursday.
"We were very ordinary today and we deserved to be beaten," said Bashar.
It was another frustrating display by the Asian side who have beaten India and South Africa at the World Cup but were completely outplayed by Ireland.
"Ireland batted very well. When we batted we lost too many early wickets. It's been a problem. We need to bat 50 overs if we are to have a chance of winning," added Bashar.
Bangladesh, chasing 244 to win, were bundled out for 169 in 41.2 overs by an Irish side enjoying their first ever World Cup which was highlighted by their famous win over Pakistan in the opening stages.
"We knew we had to get all three disciplines right today and we played the perfect game," said Ireland skipper Trent Johnston whose team had been crushed by nine wickets by world champions Australia in their last game.
"We were always going to bat first and the challenge was for the openers to get through the new ball.
"All credit to William Porterfield (85) and Jeremy Bray (31) who got through the first 15 overs.
"We didn't want to bat second against their spinners trying to chase a 220-230 total. We chose to bat first, put up a challenging total and then wanted to squeeze them."
Johnston also praised the fans who have followed the team around the Caribbean over the last five weeks.
"They have spent a lot of money coming over here and we wanted to give them a good display," he said.
Ireland's last match will be against Sri Lanka, who have already made sure of their place in the semi-finals, in Grenada on Wednesday.
It will be coach Adrian Birrell's last match in charge before he hands over the reins to West Indian Phil Simmons.
"We want to give Adrian a great send-off and hopefully we can put in another display like today," said the captain.