Boro are now languishing in 19th place in the table after suffering a fifth straight defeat on their travels.

They took the lead at Pride Park when Kris Boyd scored his first goal in seven games with a neat glancing header.

But Derby responded and, after the impressive Kris Commons had a penalty saved by Jason Steele, Shaun Barker equalised with a towering header on the stroke of half-time.

Commons then made amends for his penalty miss to score two fine individual goals in the second half to leave Boro without an away win in the Championship since Easter Monday.

Strachan said: "I look at the players and I think 'can they try harder?', but I think physically they are trying.

"Sometimes they actually try too hard and when they're doing that they play themselves out of position and leave some gaps and that's just the frustration at the moment.

"You've got to keep a hold of your frustrations sometimes, or you'll lose your shape and some players were trying to close down too quickly and got picked off. The goal just before half-time, if we'd have sat back with not some much space in between defence and midfield we'd have been okay.

"It's okay closing down but there's got to be an end product to it.

"You normally get six or seven playing well and you've got a great chance of winning the game, but I think there's something fundamentally wrong at the moment and we have to put our finger on that."

It was a second consecutive victory for Derby after their 5-0 thrashing of Crystal Palace on Saturday.

And Rams boss Nigel Clough paid tribute to two moments of class from the impressive Commons.

Clough said: "That's what he's capable of. His two goals tonight were of extremely high quality.

"He gave the ball away again a little bit too much, especially in the first half but to miss the penalty and to bounce back and score two goals like that, we'll put up with him as long as he's putting the odd goal in like that."

He added: "I thought it was a different level to Saturday. From the point they scored, I thought the last 30 minutes of the first half was as well as we've played in I don't know how long.

"It went the other way after the penalty. Maybe they thought we were going to collapse but we were worthy winners."