Yorkshire 257 (Head 54, Barker 4-55) and 78 for 5 (Clarke 4-24) lead Warwickshire 179 (Clarke 50*, Hain 48) by 156 runs
Yorkshire may learn between now and the end of the season how much they have missed Ryan Sidebottom during the seven matches he has been forced to miss because of an ankle injury. In that time they have won only twice and while there have been other factors at play, not least the weather, it is not unreasonable to speculate that, had he been steaming in, business as usual, they might have created a few more opportunities at the very least.
The veteran left-armer will be 39 in January, far too old, you would say, to be doing what he does, yet there has been no evidence during the last couple of years that his powers are waning. Last year he finished top of Yorkshire's averages with 41 wickets at a stingy 17.9 runs each; in 2014 it was 48 at 18.35.
His longevity as a bowler is a wonder, given that he hardly lopes in off a few gentle strides. It would not be Ryan Sidebottom if he were not thundering in, nostrils flaring, that familiar leonine mane adding to the sense of speed and menace. It is a testament to how well he looks after himself, and how well Yorkshire have managed his workload.
It was doubtless a little embarrassing, then, that the hairline fracture that has kept him out of action since April had to be put down not to what he did to himself in that match against Warwickshire, but to a mishap incurred subsequently, when he managed to do further damage to the same ankle playing a football game in the dressing room.
It goes without saying that the consequences of this could have been pretty depressing. Happily, though, all looks well. Reassuming his customary role as the leader of the Yorkshire attack, he bowled 15 overs, taking the second Warwickshire wicket and the last, either side of the one that happened to be the 400th first-class wicket of his Yorkshire career.
"It is a relief to be okay, a huge relief," he admitted afterwards.
"It was one of those stupid accidents that can happen and at this stage of my career, of course there is always that worry in the back of you mind. You wonder what's going to happen, am I going to be back next year?
"But Yorkshire have looked after me well, I've played the last three weeks in the seconds to get some bowling under my belt and it is great to be back and to contribute.
"We've got seven games left and if I can contribute to the team winning a couple we are going to be there or thereabouts again at the end of the season."
There was pride, too, that he had been able to add another milestone, having passed 700 career first-class wickets last season. "Dizzy (Jason Gillespie) congratulated me and announced it to all the lads in the dressing room and that was really nice of him," he said.
The bigger proportion of those Yorkshire wickets - 238 out of 401 now - have come since he returned to his home county from Nottinghamshire in 2011, when the Trent Bridge club decided the three-year contract he wanted was too big a risk. Even he thought it would be the last one he signed. In the event, he has extended it twice, to six years. Moreover, those 238 wickets have come at 20.99 runs each, compared with an overall career average of 23.99. He genuinely has improved with age.
The 400th, fittingly, was an important one, prising out Sam Hain on 48 when it seemed the talented 21-year-old right-hander could be set to compensate for the failures of Jonathan Trott and Ian Bell by bookending a string of good performances in white-ball cricket with back-to-back Championship hundreds, following on from his one against Hampshire in early July.
Trott, miscueing a pull, gave a return catch to Jack Brooks, another whose return from injury may have come at a timely moment, while Bell, on the drive, sliced a ball from Steve Patterson straight to backward point. With Hain's demise, Warwickshire were in trouble at 112 for 6.
That they managed to scrape their way from there to 179 all out was almost entirely down to Rikki Clarke, another who would argue that age is just a number. At 34 he's just a young 'un next to Sidebottom but there are a few miles on the clock. Yet as an all-rounder - batsman, bowler and brilliant slip fielder - he still stands above the rest in the county game.
He proved it here, first with the unbeaten 50 that kept Warwickshire in the game and then, in a superb evening's work, with four wickets, reducing Yorkshire to 68 for 5. He had Adam Lyth and Travis Head caught by Varun Chopra at first slip and later, in consecutive deliveries, bowled Jack Leaning with a swinging full-length ball and had nightwatchman Patterson leg before.
"To score an unbeaten 50 and then take four wickets in 15 overs made it an outstanding day for him," Warwickshire's director of cricket, Dougie Brown, said. "We needed someone to step forward and do something and that is exactly what Rikki did. He has brought us back into the game and far closer than before Yorkshire started their second innings."
Yorkshire closed on 78 for 5, their lead just 156. The pitch is dry, there is turn and bounce and what Jeetan Patel does on day three could be as important as Clarke's contribution on day two.