Pre-season offers little reliable indication of how a side will fare in the season ahead.
Sunderland's wretched league record in the opening months of recent seasons tells you that. St Johnstone, too, are well ahead in both fitness and competitive game time.
Nevertheless, the manner of this first half defensive horror show is a concern.
Simon Grayson's touchline demeanor, utterly irate for the most part, was a giveaway that this was well short of what he requires. He had started the game in the stand, yet by 25 minutes he was pitchside, a face of thunder with his side trailing by three goals to nil.
The second half saw an altogether more sedate tempo, neither goalkeeper tested. That perhaps made the surreal first half all the more bemusing.
Sunderland, who fielded about as strong a side as they could, had started by dictating the tempo, controlling the ball. James Vaughan was drawing appreciative remarks from his team-mates, winning balls in the air, knitting together the attacking play.
When Jeremain Lens darted into the box and won a penalty, a polished performance looked in the offing. Vaughan, however, hammered it too close to the keeper, who made an easy save.
Minutes later, a routine backpass from Wahbi Khazri saw Vito Mannone slip to the floor. He bundled the ball into his own net, but an indirect free-kick had already been given. St Johnstone scored from it, Steven MacLean racing onto the pass and seeing his effort deflected into the net.
Three minutes later it was two, the hosts working an easy overlap. David Wotherspoon, who had missed a sitter on his right foot in the early minutes, this time cut inside, turning Brendan Galloway too easy and finishing past Mannone.
His second, and St Johnstone's third, was scored with a swagger. Again he found space in the box down the right, dribbling past Mannone and turning home into an open goal.
Even if Sunderland steadied from there, they looked sloppy at the back, often caught dithering on the ball.
They should have gone in having pulled back a goal, however. Lens turned the left-back with a superb nutmeg, and his cross to the back post was perfect. Vaughan, with the goal gaping, could only glance a header wide.
Smart work from Wahbi Khazri minutes later sent Rodwell in on goal just before the break, but he was flagged offside. Zander Clark, the St Johnstone keeper, was badly hurt in the collision, requiring prolonged treatment before leaving on a stretcher.
Normality somewhat returned in the second half, played at a pedestrian tempo, neither goalkeeper seeing much action.
Sunderland made numerous changes, gaining a foothold in the game but unable to build much momentum and certainly never threatening a comeback. Simon Grayson will at least have been pleased to see a defensive improvement, with Papy Djilobodji impressing again with a number of excellent covering challenges.
Tyias Browning, making his debut at centre-back, showed a no nonsense approach with a couple of strong clearances.
A bad defeat, regardless. Sunderland have a great amount of time before the season starts but this level of defending in the second tier will cost them dear.