Stuart Parnaby didn't spend the first seven years of his professional football career unaware of what it's like to lose at the Riverside Stadium.
But no defeat from his Middlesbrough days tasted as odd as this one.
Maybe it was simply because Boro old boy Parnaby was back in town. Maybe it was because a fired-up Mido was playing for the team he signed for against the team for whom he nearly signed and who had a particular point to prove.
Or maybe it was because Boro manager Gareth Southgate remains indoctrinated from his Aston Villa days by the importance of being better than Birmingham City.
Yet Parnaby's former manager admitted that Boro had produced their best performance since he took over in the manager's chair from Steve McClaren 14 months ago.
The Blues defender, meanwhile, was left perplexed by the whole afternoon's events. "It was possibly the strangest experience I've ever had, especially after the game," said Parnaby.
"I had 14 years here wearing a red shirt, so coming back was really odd and so was the fact that we never really played. We just didn't get started and were 20 per cent off the pace.
"The boss was upset afterwards. You can just imagine what he was like, not best pleased. We've been very competitive so far this season and that's what we're most disappointed about but it's too early in the season to be talking about a crisis.
"We played really well at Derby County and should have scored loads of goals but we let Boro play and made it pretty comfortable for them. We didn't pose much danger, we made problems for ourselves and didn't put any pressure on the ball.
You can't let their middle two [Julio Arca and Fabio Rochemback] have so much time on the ball like that. They're dangerous."
If Boro winning the midfield battle was the key, so was the poor marking that characterised Blues' defending, a situation best summed up by the scorer of the second goal, Stewart Downing, who admitted: "I had that much time, I thought I was offside."