Opting to go for spin, Windies included left-arm spinner Fabien Allen in their side in place of Oshane Thomas, a move which backfired with the dew at Sylhet International Cricket Stadium rendering the spinners ineffective.
"We did (misread the pitch)," Powell said after the game. "If we hadn't misread the wicket we wouldn't have dropped Oshane Thomas. He is our fastest bowler and I think we needed him on that wicket. It's just one of those things, we thought the wicket will spin a little bit more and it didn't spin.
"We honestly thought the conditions would have spun a little bit more. We didn't know about so much dew at this ground; it's even more dew than what was in Dhaka. We are just reading conditions wrong and that is just a part of human nature."
Windies managed just 198/9 in their 50 overs riding largely on Shai Hope's second successive century of the series. The hosts then faced no threats in chasing down the meagre target as they romped home in 38.2 overs with Tamim Iqbal (81*) and Soumya Sarkar (80) leading the chase.
Powell congratulated Hope on his magnificent 131-ball 108* but had no fuss admitting that performance of all other batsmen, including his need a lot to be desired.
"Shai Hope batted beautifully throughout the entire series. We can take a lot of courage from him," said Powell. "In both games, he stood up and batted fifty overs. He showed that the wickets here in Bangladesh can do well on. It's just about applying ourselves.
"We have to say congratulations to him. But through the entire series, the batting unit didn't stand; it has been a problem for us over the last few series and, to be honest, we aren't improving.
"West Indies are T20 champions. We have a very good T20 team. We just have to get familiar with conditions. We know that there is a lot of dew and it is a good wicket and come out and play the brand of cricket that West Indies want to play."
Mashrafe Mortaza, the Bangladesh captain, on the other hand, was over the moon after his side bounced back after losing the second ODI with a clinical performance to seal the three-match series 2-1.
"Combination is important for a team. Not that we always get it right but execution is more important. The bowlers executed their plans today. Winning the toss was vital too but the bowlers did the work for the batsmen. It is all about execution and holding your nerve," Mortaza said after the win.
Mehidy Hasan, who broke Windies' back with figures 4/29 said winning the toss helped Bangladesh as there was slight moisture underneath the surface early on that helped the spinners grip the ball better.
"Luck favoured us because Mashrafe bhai won the toss," said Mehidy. "The wicket had slight moisture with help for spinners early on in the game. It was great to bowl eight overs from one end. It is difficult to bowl with the new ball, especially with two fielders outside the circle.
"But good balls bring more opportunities for wickets. I try to bowl in the right areas and not give away boundaries."
Bangladesh travel to New Zealand next where they play three Tests and three ODIs in the month of February-March 2019. Having had a good record in the last 12 months or so, especially in the 50-over format, Mortaza sounded confident that his side will be able to deliver the goods in New Zealand as well.
"Winning eight out of 12 ODI series makes it clear that we have progressed, and we are playing with confidence," he said. "We have the New Zealand series coming up. It is an important series for us since we lost to them last year. I think we have a more balanced side, and we hope to do well there."
First Published: December 14, 2018, 11:09 PM IST