Being men's Sri Lanka captain can occasionally feel like a no-win situation. To begin with, you're in charge of a side that has failed to seriously arrest a six-year decline. (It's been said for ages that Sri Lanka are "in transition", but as they are seventh on the Test rankings six years after their last great batter retired, maybe the transition is complete, and they are now just a much worse team).

Such has been the turnover of the captaincy across formats, you've also got to watch your back at all times. The previous Test captain, Dinesh Chandimal, was dumped - not just from leadership, but from the team altogether - following a bad tour of Australia. Not long before that, Angelo Mathews was sacked from the limited-overs job for (and this is honestly the official reason) being too chonky and running out too many partners because he was chonky.

And then, there is elite cricket's premiere manufacturer of industrial-strength buffoonery to deal with, aka SLC. Maybe you're a new captain and you want to build a productive relationship with the coach? Look, this board is big on their hiring-and-firing. The coach will be out of here soon enough. Or maybe you want some consistency in selection? Hard luck, friend. Try again. Or perhaps you're hoping that whenever a player gets injured, there's a decent Test-ready substitute waiting to take his place? Lol. Have you seen the first-class system? Disciplinary hearings, embarrassing media releases, player names spelled wrong on jerseys, shouty press conferences, greasy politicians, money being skimmed on broadcast deals - this is life.

Into this infuriating set of circumstances, drop a man who seems almost impossible to infuriate. Affable. That's Dimuth Karunaratne. When his keeper insists on a terrible review, he smirks. When catches go down; no wild gesticulations. Wry smiles, pats on the back, a quiet word - these are the signature Karunaratne moves. When you're operating in the upper reaches of a system as maddening as this, to be this inoffensive is not far from being an achievement.

Perhaps most importantly, the man has just stuck around. He's kind of made it his thing. Years before he led the team, he was constantly on the verge of being dropped, but dusted off a 64 here, a 77 there, and made himself difficult to be parted with. This has gone on for so long that when he has lean spells now, it almost seems inevitable that a score is coming. In South Africa, in December and January, he began with 22, 6 and 2, before signing off with 103 - at The Wanderers no less. Similarly, in the West Indies, he'd hit 12, 3 and 1, then an important 75 as Sri Lanka strove to draw the second Test.

In this innings on Friday, he made the least convincing start out of the five Sri Lanka batter to come to the crease, scratching around, playing and missing, failing to pierce the field, making only 16 from his first 65 deliveries (in the same period, opening partner Lahiru Thirimanne had made 43). There was almost a return catch, big lbw shouts (one of which was given out and overturned), running stutters, and periods under which bowlers put him under substantial pressure. But oh, look, end of day, there's an 85 not out on the scoreboard, and, well, who should it belong to but this guy? That it was made at the relatively sedate strike rate of 40 should surprise no one.

As with his batting, his tactical nous as captain has never been spectacular, but neither has it been terrible. He attacks with the field, but has the misfortune of captaining a profoundly fragile bowling attack (Lahiru Kumara seems to have tweaked a hamstring and may be out of the series). When it became clear that the pitch was offering his bowlers less than nothing in this match, Karunaratne changed tack and got them bowling dry - attempting to frustrate the opposition since they could not be blown away. Captaincy that is far from inspired, and yet, not completely unfruitful.

He's no one's idea of perfection (as opener or captain), but right now, he's what they've got, and like a good stepfather, or a substitute teacher trying to get the class through the syllabus, the guy is making a fist of it. When Bangladesh made 541 in the first innings, Sri Lanka were essentially in a no-win situation. And bless him, Karunaratne hung around.

Andrew Fidel Fernando is ESPNcricinfo's Sri Lanka correspondent. @afidelf