Steven Smith hooked Mark Wood for six. It was a beautiful shot, but the feeling it gave was more of surprise. That is not how Smith has been playing the short ball of late.

Even with only one fully functioning genuine fast bowler - who hasn't played every game - England have dismissed Smith with three back-of-length balls this series. Wood has him twice, and Ollie Robinson took him in Adelaide.

Smith has struggled a little more against spin in recent times, and the length ball has also troubled him. But nothing has changed more than how he used to handle balls above the waist like it wasn't a big deal. Now it gets him all the time.

It wasn't always like this. There was a five-year period from September 2014 where Smith averaged 96.2 against seam bowling (with a minimum of 1000 runs in that period). The next best was Kane Williamson, averaging 55.8.

Smith was nearly double his nearest contemporary. He transformed from a part-time legspinner who Ricky Ponting didn't think could be a top-six player, into the greatest modern batter, and not even by a little bit; the runs he scored were incredible. Making a hundred every 2.1 Tests. His overall average in that period was 78.7. Eight scores over 150. The whole thing was crazy.

Since September 2019, Smith has averaged 40 in Tests, which in recent times is not terrible. It is only terrible for him because he was so much better than anyone else. And in that peak five-year period, he also missed a year because of Sandpapergate.

Smith came back from that and never missed a beat, allowing the redemption hawks to squeal over it all. And then Jofra Archer hit him on the neck, and things changed (although even before Archer hit him, Smith was out to the short ball twice at the 2019 World Cup).

Around the middle of 2017, batters worldwide suddenly stopped playing seam bowling as well as they had. Marnus Labuschagne changed Australia's batting order. Smith's elbow became a concern. And he got older. And teams around the world started bowling a different line to him.

It was the line that was first noticeable. Smith scored 144, 142, 92, 211, 80 and then 20 in the 2019 Ashes. It was in the last Test at The Oval that it seemed like England bowled a lot straighter to him. Gone were the very wide balls; now they were bowling at his stumps or body. Chris Woakes had him lbw in the first innings and Broad had him caught at leg gully in the next.

That Test started on September 12, 2019.

In that five-year wonder period before, 20% of the deliveries from pace that Smith faced were very wide outside off stump, the idea being to keep the ball away from his strength and turn it to the legside. From that Oval Test onwards it has been 7%.

The drop-off also hasn't come away from home. All but one of the Tests since September 2019 have been at home; in that glory period, he averaged 96 at home and since then it's 39.

Smith hasn't been entirely healthy in this period. In 2019 he underwent what is known in baseball as a Tommy John surgery, on the ligaments in his elbow. The problem flared up again before last year's T20 World Cup. Those are the years he's struggled slightly more.

He's also just getting on. One of the more common thoughts was that Smith would stop scoring runs as his reflexes went one day. He is now 32, so it would seem that this is the age where it could catch up with him. Except if that was happening, you would assume we'd see a bunch of wickets that are bowled and lbw as he moves across the stumps and misses them. That's not where his dismissals are coming from. It's from back-of-length balls.

This takes us back to the Archer bouncer. Because Smith has struggled with shorter balls since that hit.

He's now been dismissed by back-of-length balls and bouncers 10 times since September 2019 (including that Test at The Oval) in 22 innings. In his golden run, he was dismissed 10 times by similar deliveries, but from 77 knocks. Before it, against those deliveries, he averaged 117, scoring at 3.67 runs per over. Since then it's been 23.7 at 2.3.

Four of those dismissals are to Neil Wagner, although that in itself isn't interesting because Wagner bowls short to everyone. In the 2019 World Cup, before that Archer hit, New Zealand had dismissed Smith with a short ball and legside catcher. The West Indies also got him with a bouncer. It's possible that Archer hitting Smith was actually part of an existing problem, not the cause itself.

Another factor often mentioned is that Smith has been getting bored since Labuschagne settled in at No.3. This is known as the 'Twiddling the thumbs' theory: that, effectively, Smith has become so bored watching Labuschagne and David Warner bat long that he struggles when he does go out to bat. ESPNcricinfo's stats team looed at this - Smith walked into the wicket with the median score at 52 for his glory run, and it has been 100 since. However, he also batted at three a bit more in the glory years, even if he was a specialist No.4 more often than not.

It might be best answered really though by looking at his failures. Post the 2019 Ashes, there are eight times he arrived at the crease with the team score over 100. In three of these innings he passed 50. There are six times he entered the crease when the score was not yet 50. In only one of those innings he passed 50. If there is a pattern here, I am not seeing it.

And while Warner has a big average recently, he has only passed 50 on five occasions since that Oval Test. Australia has used three different openers that aren't Warner. So there has been plenty of opportunity for Smith to come in early if that was a problem.

There is always a rush to call the end for greats. But the fact Smith can still hook Wood for six tells you he's not finished. Averaging 40 at the moment is still pretty good. It's just not good for Smith.

From this, you'd have to argue that he's not failing because he's twiddling his thumbs. He's getting in similar times to before, often making starts or even 50s, and then being dismissed.

But something else has changed within cricket recently. Smith is not the only person struggling against seam bowling. In the last four years, the global batting average against seam bowling is 26.7; in the four years before that it was 32.02. That's a huge drop.

It doesn't explain Smith's form. In fact, there seems to be no one thing. Balls above his waist are clearly a problem, but he's struggling on a length and not as dominant against spin as he once was. He might be getting bored by Labuschagne and Warner on occasion, but there's no pattern suggesting a real problem. If his reflexes are a problem, it's weird he's not being dismissed when the ball is straight and full and he's flicking across the line. His elbow is probably going to be an ongoing issue. And yeah it's been tough to face quicks, but not enough for him to be nearly two-thirds worse against it.

There is always a rush to call the end for greats. But the fact Smith can still hook Wood for six tells you he's not finished. Averaging 40 at the moment is still pretty good. It's just not good for Smith.

It would be very easy to doubt that Smith can regain that old form. But, everyone doubted he would ever be a top Test batter, and for a long time, he was by far the best. If anyone can work it out, it's probably him.

Jarrod Kimber is a writer for ESPNcricinfo. @ajarrodkimber