The Blues put in another dismal performance on Tuesday night to see them trail on aggregate in their Carabao Cup semi-final.
Cole Palmer missed two excellent chances to score and Hayden Hackney's first-half goal was enough for Middlesbrough to win.
It means Chelsea have it all to do at Stamford Bridge in the second leg in two weeks, with a vast improvement needed if they are to win.
After the full-time whistle, Jamie O'Hara and Dean Saunders called former Blue Cundy for his thoughts, and it's safe to say he was far from happy with what he saw.
"I am absolutely fuming with that, genuinely fuming. How many times have I said this to you?
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"I've read this book, I know this game, I've watched it dozens of times this season... we couldn't break down a sandcastle. We would be there until this time tomorrow, honestly it's infuriating.
"[Nottingham] Forest at home, Brentford at home, parts of [Aston] Villa, West Ham away, now you can add to that list, Middlesbrough away.
"And I tell you what, if Middlesbrough play like that and defend like that, they're going to Wembley. Honestly I'm fuming, I'm absolutely fuming."
He added: "I don't see any different approach to that than I did against Forest, against Brentford, it's the same story.
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"Credit to Middlesbrough, credit to [Michael] Carrick, they get their tactics right... but their goalkeeper by the way, he's a nervous wreck! No cutting edge, no final through ball, honestly the final third... I'm absolutely fuming."
Cundy went on to further lament Chelsea's performance but was able to find one positive from the defeat.
"What have I just watched, what have I just seen? It's the same story and by the way, our best chances came from Middlesbrough.
"Defensively they were brilliant, but how many chances did they give us in the first-half? Palmer could have had a hat-trick, but two of them could have come from them, the only one that we carved open was [Moises] Caicedo on the edge of the box.
"The only saving grace is that it's half-time, that's the only positive I can take out of this."
Chelsea face Fulham on Saturday before having a ten-day break to prepare for the second leg against Middlesbrough.
The Carabao Cup is one of two likely chances for the Blues to win silverware this season, but they may have left themselves with too much to do.