Byas struck a century full of power and fluency, with forthright shots that included a mighty six off Kevan James, although it said much about Hampshire's efforts in this almost certainly short-lived competition that his 100 came up off a misfield.
The visitors' shallow total always looked distinctly attainable and as soon as Byas and, to a lesser extent, the Australian Greg Blewett, got into their stride, heads drooped visibly among the visitors.
Not always timing the ball, Blewett rather stuttered to his own share of the partnership before falling to Nixon McLean with two runs needed, which duly arrived off McLean's next delivery, a no-ball, and all this after Hampshire had set the pace at the start.
Yorkshire's early bowling was wayward, especially that of Chris Silverwood, back after a knee injury to try to claim a Test place. His first over went for 13 and Jason Laney, continuing some productive form this season, was soon in the 30s.
Even when the opening stand was broken, it was the result of Derek Kenway chasing a wide one from Gavin Hamilton. Laney also fell to Hamilton and the Hampshire innings never recovered its momentum.
They were not helped by some variable bounce; their captain, Robin Smith, being caught off his glove when a ball from Craig White reared horribly, one of four chances accepted by Richard Blakey.
Will Kendall managed a stubborn 28 and Shaun Udal thumped one big six off White before being caught trying to repeat the dose.
Hampshire were largely dependent on John Stephenson for even their modest total, however, and the former captain remained undefeated at the end. Despite his efforts, a score of 187 did not look sufficient once Yorkshire's openers got to work.Reuse content