Despite posting 11 scores of 150-plus, including four over 220, they finished fifth in the North Group, just outside the four qualifying spots.
Anything less than a quarter-final place this time would be no less surprising, particularly with the club set to be strengthened by the return of several England players later this month, along with overseas batsman Kane Williamson.
Even without those players they are still a formidable prospect, as they proved at Headingley by winning their opening game in this year’s competition, beating Durham by 44 runs despite an unbeaten 90 from England’s Ben Stokes.
Yorkshire’s standout T20 player last year was Adam Lyth, who gave them some flying starts at the top of the order.
When Lyth last batted for Yorkshire in a T20 match he scored an English-record 161 against Northants at Headingley last August.
Yesterday the left-hander achieved his second-highest score in the 20-over format, an unbeaten 92 that underpinned a total of 200-3 after Yorkshire were put into bat on a hot and sticky night.
He faced 54 balls and hit 12 of them to the boundary in the form of nine fours and three sixes, his in-to-out strokes through the offside, in particular, a joy to behold.
Lyth also received splendid support from two men making their T20 first-team debuts for the club.
Jonathan Tattersall, the 23-year-old wicketkeeper who has recently come into the first XI and looked as though he has been a fixture in it for years, hit an unbeaten 53 from 27 balls with six fours, sharing an unbroken stand of 110 with Lyth in 8.5 overs, 93 of those runs coming in the last six overs of the innings.
And Harry Brook, the 19-year-old who has made such a stirring impact in the County Championship, struck 44 from 31 balls with four fours and two sixes, displaying, like Tattersall, finesse as well as force.
It was great entertainment for a sun-kissed crowd of 7,088, not least because Durham by no means bowled or fielded poorly.
Where Yorkshire were good was that they did not panic and throw flurries of wickets away in response, the hosts content to rotate the strike whenever Durham made it difficult to find the boundary.
On a cream-coloured pitch that played well throughout, Yorkshire recovered strongly from the blow of losing the dynamic Tom Kohler-Cadmore in the second over, the England Lions man skying to mid-wicket.
Brook was fortunate not to perish without scoring when he sent his second ball through the hands of Will Smith at point off James Weighell, which would have left Yorkshire 9-2.
But there was nothing fortuitous about the strokes that followed from the teenager’s bat, nor from those of Lyth and Tattersall.
Brook looked set for a big one only to loft leg-spinner Imran Tahir to Tom Latham at long-off, Tahir making history by becoming, aged 39, the first man to represent seven different counties – including Yorkshire, for whom he played one game without success 11 years ago.
After Brook’s departure left Yorkshire 90-2, the hosts slipped to 90-3 when Gary Ballance fell for a golden duck, brilliantly caught by Latham, diving forward right-handed at cover, off a leading edge off the spinner Ryan Pringle.
But Lyth went to his ninth T20 fifty from 38 balls, Tattersall showed plenty of improvisation, and the only shame for the crowd was that Lyth did not quite have enough time to raise his hundred – although he did his best, going from 51 at the end of the 17th over to his final tally of 92.
When Durham replied they were immediately rocked by some excellent bowling first up as the Yorkshire bowlers hit the pitch hard.
Jack Brooks was devastating from the new Emerald Stand end, taking two wickets in three balls to reduce the visitors to 13-2, Graham Clark top-edging to deep mid-wicket and Paul Collingwood trapped lbw for a golden duck.
Steve Patterson had Latham caught around the corner to leave Durham 45-3, but Stokes and Will Smith lifted the total to 91 before Brooks returned to have Smith pulling to deep mid-wicket, the pace bowler finishing with 3-21.
For as long as Stokes remained there was still an outside chance of a Durham win, the all-rounder making his first appearance since tearing his left hamstring in the build-up to last month’s Headingley Test.
Seeking to prove his fitness for Sunday’s T20 international against India at Bristol, Stokes struck eight fours and five sixes in his 68-ball innings.
But Stokes sustained a blow to his foot in the process when he accidentally hit the ball into it and never quite seemed 100 per cent.
Ultimately, the target proved beyond the visitors, who closed on 156-4, Steve Patterson and Azeem Rafiq playing their part in an ominous Yorkshire performance.