Glasgow in particular face a tough shift against Leinster in Dublin where Barclay fears Danny Wilson’s side will be overpowered.
The Warriors go into Saturday’s game on a run of four defeats, the most grievous being the 28-11 reverse against Edinburgh.
The former Scotland captain believes the visitors let the occasion get the better of them at Murrayfield, with experienced forward Rob Harley sin-binned.
“They’ve had a tricky run of fixtures,” said Barclay, who will be covering the Leinster-Glasgow match for Premier Sports. “But the biggest disappointment for me was the Edinburgh game when I think they just got too caught up in the emotional side and forgot to also have a look at the technical and tactical part. Their discipline was very poor.
“So, I don’t think they are in a good spot. You certainly wouldn’t plan to go into a play-off game off the back of four losses on the spin. I don’t think they’ve got enough in their form or in their play at the moment to compete with Leinster for 80 minutes.
“I hope they can, obviously. There is a lot of talent in that squad, but they’re just not quite clicking at the moment and there are too many frailties to their game.
“I think Glasgow are lacking a bit of power up front, but they’ve got enough there that they should be able to pass muster with George Turner playing well at hooker and Zander Fagerson at tighthead prop. They are a bit light in the second-row and missing a few in the back-row as well.
“In any situation when you’ve had four losses you’d look to the senior players to give a bit of guidance, but apart from Ryan Wilson – who I thought played very well – a lot of the other senior guys didn’t have their best games.
“When you have one of your most senior players getting sin-binned for a crazy offence when you are up against it, that speaks to a team that’s under pressure, panicking a bit and is frustrated.”
Edinburgh, who are in South Africa to play the Stormers, finished the season just four points above Glasgow but the derby win gives them momentum and Barclay has been impressed by Mike Blair in his first season at the helm.
“It is pretty remarkable what he has achieved,” said Barclay. “He inherited a squad that probably was not suited to the style of rugby Mike is trying to play. He has come and shown that the guys there have that capacity to change and they love the environment, there are smiles on faces, the brand of rugby they are playing is great.
“It still needs to mature a bit but Mike has done a great job in his first nine months in charge.”
John Barclay will join the Premier Sports team of Ross Harries, Rob Kearney, Stephen Ferris and Ryle Nugent for full build-up and live coverage of Leinster v Glasgow Warriors on Premier Sports 2 on Saturday from 3pm. Tune-in to the drama on Premier Sports - sign up at www.premiersports.com