A goal in each half from Gaston Ramirez and Stewart Downing condemned the Cherries to defeat on Teeside, two goals that Francis said could have been avoided.
The skipper told BBC Radio Solent: "The fans were great and I could hear them all game.
"The fans came a long long way and turned out in thousands as they do - it's really disappointing we couldn't get a result for them.
"The first goal is a counter attack from our own corner, that's something we have to nullify. We pride ourselves at locking out those attacks, we maybe could have given away a good foul in that situation and regroup – to put it bluntly.
"We were getting a foothold in the game before the second one, Negredo has peeled off me, it was a good knockdown and someone arrived at the back post, it was a real sucker punch. They have to be avoided.”
After going unbeaten in the last five Premier League games, Francis labelled the reverse against Middlesbrough a wake up call and expects Saturday’s opponents to stay up this campaign.
"We didn’t dominate as well as we can do, confidence has been really high so maybe we took our foot off the gas and that’s a credit to Middlesbrough," he continued.
"They have good players and a good squad, a real togetherness so I think they’ll stay in this league.
"Its strange, last season we were struggling at home and doing well away and it’s a complete reverse so far. We need to try and find a balance, it’s a bit of a wake up call."
