The 'inevitable' Celtic second wave underpinning Ange Postecoglou's Parkhead revolution

The below graphs probably reinforce what we already think we know about Celtic under Ange Postecoglou: they love a fast start.

What the data does throw up, though, is that it mightn't always be as fast as they'd like.

While the Hoops have scored no goals in the first five minutes of a Premiership match so far, that increases to three when we widen it to the opening 10 and five in the first 15.

That's all well and good but, for the purposes of this article, we'll be dealing with StatsBomb's 'match time' graph. As such, the timeframes we'll consider are diced up roughly in accordance with the graph's peaks and troughs.

Handily, these are pretty easy to follow. The first wave is from kick-off until the curve starts to slope downward again around the 30-minute mark. Then comes the relatively slow period bridging the times directly before and straight after the half-time break. After that is the second wave, from around an hour in until the final whistle.

The first wave helps illustrate Celtic's propensity for maintaining their early threat - it reaches a crescendo around midway through the half, just when you'd expect opposition mistakes to start creeping in if Postecoglou's trademark 'don't stop' intensity is taking its toll.

Indeed, 16 of Celtic's 39 Premiership goals this campaign have come during those first-wave attacks - that's a massive 41 per cent and comfortably more than in any other timeframe.

The corresponding total xG for all the shots they've taken in this slot is 15.7, so they are performing about as expected in front of goal based on the chances they create in the early stages. On the defensive end, they've conceded four times during the first wave (3.02 xG).

The intensity tends to tail off slightly in the period before half-time, with four goals in the final 15 before the whistle. After the break, it's an altogether slower start than the opening 45 but still a more fruitful spell than what directly preceded it with seven goals before the hour mark.

READ MORE: Which Celtic players add the most value? 

Even during Celtic's so-called down period, then, they pose a decent threat with 11 goals, albeit in a slight underperformance compared to xG (which is 13.15 for that timeframe). In this phase they've also conceded four (3.06 xG) so although they are less likely to score they're not really any more likely to let one in as a result.

And then the second wave hits.

Interestingly, while the Celts have scored only one more goal (12, though that's including two converted penalties) during this phase than their 'down period' they actually create a lot more opportunities.

Their second wave non-penalty xG of 16.58 is higher even than the first wave. The problem is they simply don't finish as clinically during the second wave which, all things considered, probably fits in well with the narrative of the season so far and is arguably the area on the field most up for improvement.

So even though they might not reach the threatening heights of the first half every time, Celtic do consistently rise again for most of the final 20 minutes. There's a natural tailing off slightly in the dying embers - natural in the sense that the Hoops don't often go into that period trailing or even in need of a winning goal - but it should be noted no team's curve trends upwards in the final couple of minutes and, in fact, most start fading before that. 

To help make that clearer, the following three graphs are included. The first two belong to Rangers and Hearts from this season while the third is Celtic's from the last campaign. 

The main takeaways from these are that Rangers tend to peak right before half-time before fading in the last half-hour or so, that Hearts not only take until the second 45 to reach their apex but are actually more likely to concede than score for sustained periods and, perhaps in the most obvious contrast from this season to last, Celtic 2020-21's goal threat falls off pretty dramatically in the final half-hour. There was no second wave last term.

Of course, with players of the quality Postecoglou possesses, a persistent menace in front of goal is almost seen as a given.

But the broken down data here is enough to reinforce what most opponents should probably have learned by now... they cannot afford to switch off against this Celtic side until the final whistle has gone.

Postecoglou told everyone from day one his men 'don't stop' - the numbers suggest they're not going to. Just imagine if he gets to add some depth to this equation in January.