They started off with long runs on the hard. They may have had some faster laps planned but the red flag put an end to that. I wouldn't worry about it just yet. Commentators were saying the car looks well balanced.
Their medium runs were a long way off the leaders already. 1:16.4 for Lando just now on softs, almost a second off.
But this is an absolutely horrid swing of performance. If this turns out to be the same gap in qualifying tomorrow then that means they lost 0.7s to AlphaTauri between two race weekends. That's huge.
But not completely unexpected. McLaren were quick at Bahrain last year, but were slower at Imola. The car's strengths/weaknesses are relatively similar given the development restrictions being required for the PU. Alpha Tauri had a bit of a false race position in Bahrain, they were quicker than the results show. This is going to be an arduous season.