The equation used to be pretty simple. Concerts were either good or bad; you were euphoric or you were catatonic. Sometimes you were neither, but only when the event was so bland that it denied you the opportunity of forming an opinion.
Elvis Costello rewrote the rule book on Friday night with a performance that was beyond mere patchiness, that veered dramatically from one tune to the next, lurching from the unlistenablc to the irresistible.
There were excuses for the lesser moments. The singer apologised both for the state of the stage equipment, which had apparently met with a rather nasty accident avant gig, and for playing the Entertainment Centre itself, a giant squash court designed to showcase spectacle, not emotional power.
It appeared those malfunctioning keyboards may have contributed to the difficult sound mix, which was perfect during the slower numbers but worsened with every upward notch in tempo.
Not that the Rude 5 (there were three of them) made their job any easier. With the sunglassed and increasingly Jerry Garcia-like Costello down front at the mike, the rest of the band huddled together with their equipment at the back, seemingly attempting to draw any attention away from themselves.
On a stage the size of the Ent Cent's, they were lost and faceless. But at the risk of cliche, an Elvis Costello concert with a few question marks over it was still much more interesting than most shows.
Never content to play the usual Pavlovian rock role-model games with his audience, he delights in teasing with major reworkings of material, taking his songs on excursions into the unexpected which elicit a surprising range of response in both listener and performer. Six bars into the song you're listening intently for a musical figure, waiting for the smile of recognition, but even when it comes, usually only with the introduction of lyrics, you're not on much safer ground, because the abrupt directional change is always just around the corner.
Comfort and familiarity, mainstays of most rock concerts, are illusory. Slicing disparate fragments of songs together to create medleys or just rearranging single songs into textural epics, he is a master of the neat turn and sonic implosion.
As in "Couldn't Call It Unexpected No. 4," which glued quirky, waltz-time instrumental passages into a song dominated by alternately clunky and lyrical piano melodies. Or "Watching the Detectives," which began as a jazzy doodle before thrashing upwards towards a killer chorus that never came, its dynamics fiddled with at every opportunity.
The highlight was an atmospheric "So Like Candy," heavy on vocals and Twin Peaks keyboards, which dwindled into the stark "Want You," a bare-bones lament that ground relentlessly to a noisy climax before giving way to a dawdling version of the 1934 big band chestnut "The Very Thought of You." Twice in the medley the instruments dropped out to reveal stunned and appreciative silence on the part of the audience.
That he could reach this sort of pinnacle once in a set was a mark of the man's value. That he almost scaled the same heights another half dozen times, wrestling to hold the concert together, was simply astonishing.