Munster Rugby Open Training Session, Irish Independent Park, Cork 16/8/2019 Thomas Ahern Mandatory Credit ©INPHO/Billy Stickland

The Young Bucks // Tom Ahern – Part 3

There are three big pillars in every forward’s game.

Attack, Set-Piece and Defence. We’ve looked at Thomas Ahern’s growing skills in attack and at the set-piece earlier in the week and this article will track the other big pillar of Ahern’s game – defence. Defence for a second row forward takes up a big percentage of their overall perception. Even with the segmentation of pack roles, a second row who isn’t an effective, involved and impactful defender is going to struggle to be consistently selected at any serious level of rugby.

So how does Ahern stack up here?

Well, first, we have to look at the things that tend to cause problems for tight five forwards from a defensive perspective and go from there. At 6’9″ and 17.5 stone (at the moment) you’re primarily going to be a central defender – that is to say, defending closer to the ruck.

On central positions, you’ll look to track either side of the ruck, ensuring you “stay alive” as much as possible and leading line speed. That means avoiding actions that take you out of the subsequent phase without good reason and making impactful, dominant tackles or breakdown entries that either turn over the ball or slow it to the point that the defensive shape can reset.

On wider rucks, you’ll want to make sure that you’re filling whatever defensive spaces you see but, once again, you’ll ideally be in that central “C” position leading the defensive line speed.

Tight five forwards are usually your biggest, heaviest forwards and with that comes certain limitations on their movement or, rather, their ability to move. You don’t want them defending a whole lot of lateral space.

Think of it like this, the bigger and heavier the forward, the smaller the lateral space you want them covering.

You want your second row forwards defending in an area where they don’t really have to worry about what’s going on alongside them. We want them running in straight lines at a relatively shallow target. Their defensive range should, ideally, look like a rectangle (left).

What we don’t want, is a lock defending a big wide square (right) of space far-away from the previous ruck. In spaces like that – such as after a scrum or lineout – big locks can be cut to pieces by smaller, more agile players if they don’t have good defensive cover around them before returning to settled phase play.

Ahern is no exception to this general rule.

The spilt ball on the first tackle creates a “crisis” in the Irish defence and we don’t react very well. The ball hopping loose basically acts like a tip-on pass which traps a lot of defenders on the post left side of our defensive line. We then lose three players to the contact area (two tacklers and one unsuccessful jackal) which leaves us exposed on the post-right side. This is a typical “bad fold” and essentially, it means that we have five players defending 45m of lateral space with a fullback in the secondary defensive line.

Ahern is the “B” defender in this instance but he has a massive square of space to defend.

He has roughly 5m of space off his right shoulder and 10m off his left. He’s got 6/7m in front of him with a carrier and two legitimate passing options off either shoulder to worry about.

There are no “good” decisions here for the defender. Only a decision and then a roll of the dice.

Ahern gets caught in no man’s land and Scotland score under the posts. This is always the danger for second-row forwards when they are defending. This instance wasn’t Ahern’s fault – he’s doing the best he can to cover the space left by others – but it does show what happens when you have a tight five forward defending in space.

This is why the ability to track with the defensive ruck position is so important and your “track” is directly linked to your ability to keep up with the pace of defensive press. If you’re a forward, that is a key metric.

If you find yourself defending in wide spaces – even with good support – you cannot be the slow cog in the press or your very presence creates a dog leg on a blitz.

The blue line in the below graphic represents a defensive advance. The farther out from the ruck you are, the more vertical space you have to cover. If #4 cannot keep up with the pace of the defensive press, they will create a dog-leg that opponents can attack.

So certain tight five players (the likes of Devin Toner or Lood De Jager spring to mind) are not suited to these positions and have to adjust their positioning accordingly off scrum and lineout so they don’t end up defending edge spaces all that often. Not every team will blitz on these phases as it’s dependent on what the opposition are doing but if they carry wide, then you have to cover that width.

Tom Ahern ability to cover in these wide spaces is actually quite good when he has adequate support around him. He’s well able to keep up with the pace of the press and his long strides.

He starts off this phase in quite a wide position but, after the first tackle, is able to advance deep into the opposition line to get a block on a kick through.

He doesn’t panic, or over blitz, or compress onto the player to his right. He’s got the pace to keep up with the play and confidence in that pace. When tracking closer to the ruck, he’s got more than enough pace to pillar up, take the B/C position and, on occasion, defend effectively further out as long as he has adequate support.

On transition defence, that pace (and confidence) is even more apparent.

Look at his tracking on this kick transition.

That’s a lot of distance covered in a few short seconds with good decisions all the way through. He’s staying alive on the play as much as possible.

Here’s another example of a track closer to the ruck where he could have made a go for the ball at the breakdown after the first tackle but he bounced out to “B” and ended up making a key tackle.

This kind of decision making is quite important because, as discussed earlier, staying alive on plays as much as possible is a hallmark of good defence.

When he does choose to have a cut off the ball, he’s got a strong jackal which, at 6’9″, shows good attention to technique.

He just misses the ball but the timing and agility are good. He draws two cleaners and slows the ruck down to 4 seconds.


Defensive tracking, positioning and breakdown decision making is one thing – an important thing – but can he drive a fella back on his arse? The subtler parts of defence aren’t worth anything if you aren’t capable of driving a shoulder into your opposition’s gut and put them back.

Defence is a technical and emotional skill. If your defence isn’t personal to you – “they will not run me over” – then you’re only half a player, just like if you’re all hit and no brains, you won’t ever be in the right position to do your job properly.

In this regard, I’ve really liked what I’ve seen from Ahern.

He’s got great tackle technique and he’s well capable of making big, dominant stops.

This one is exactly what we want from our line speed leaders. He’s perfectly positioned, confident in his approach, he has a fantastic low tackle entry and he makes the stop behind the gain line.

He’s using his size and athleticism to get into dominant, strong defensive positions. One tackle in particular sticks out to me.

The technique on this dominant tackle is spot on.

He’s low, his head is on the right side, he’s grabbing in and up behind the knees to take away his opponent’s leg drive and he’s powering through strongly with his legs to finish. That is ideal.

Ahern is a great scrambler – this is informed by the pace and athleticism we’ve gone over at length – and this means he’s got the ability to match a potential linebreak and get a stop on the ball.

One aspect of Ahern’s game that I really like is how he uses his frame and wingspan to attack the opposition’s possession of the ball.

Some of Ahern’s best defensive work has been when he’s been able to ride out the initial contact and get his long arms intertwined with the ball.

As he grows into his senior pro frame, that ability will only be enhanced because, as with a lot of things, Ahern has so many natural gifts that you can’t coach mixed with all the things you can coach. You can’t coach a guy to be 6’9″ with a massive wingspan but if you can coach that guy to be a really good technical defender, you’ve got a potentially special player on your hands.


When you consider the three pillars of Ahern’s game you can’t help but conclude that you’ve got a potential star in the making. It would be somewhat normal for a second row at his age – only 20 since February – to be a bit unbalanced with their skill set. You often see high potential guys who might have two of the three pillars in pretty good shape (the set-piece being a constant, usually followed by defence) but who typically fall down on the offensive side of the ball. Ahern’s skills with the ball in hand, his pace, his athleticism and prowess in contact coupled with his attacking instincts make him a high potential player in all parts of his game.

The only part I think needs a fair bit of work is his scrummaging and even then, that’s something that comes a bit late to most young second rows. This is a rare combination of the size you’d want in a lock coupled with the kind of attacking variety you’d look to plug into a player over the first few years of his career. Ahern can already finish from long range, he can already pass accurately, he can already offload out of contact.

All he needs now is a graduated approach to transitioning from being an u20 academy player playing age-grade rugby to the senior ranks. This is where it gets complicated. Ahern has already featured for Munster during pre-season friendlies but is yet to make his senior debut. Comparisons with James Ryan will be inevitable but they need context. Ryan made his international debut with Ireland in 2017 before he ever played a senior game with Leinster and, from there, pretty much became first choice for Leinster thereafter before nailing down his Irish place in the 2018 Six Nations.

But you might have noticed some missing time there.

James Ryan was brought into the Leinster academy in Year 1 directly after the historic U20 World Championship run of 2015/2016 but he missed almost the entire next season with a serious hamstring injury. That’s why he got a run with Munster in a development game before going on the tour to USA and Japan that year – he had very little rugby played since the u20 World Championship up until that point.

What kind of senior game time would we have seen from Ryan had he not been injured that season? We’ll never know, but I doubt he would have been thrown straight in at the deep end. He came out of his time injured with excellent conditioning and the extra functional KG’s he would need to thrive at pro-level added on.

Ahern will probably need to follow the same pattern, ideally without the catastrophic hamstring injury that Ryan suffered.

This means a run in pre-season, a few starts against some of the lesser PRO14 lights and then gradual escalation from there. If he’s doing well against Cat C PRO14 opposition (at home to the Kings, or Dragons, Zebre, etc) then scaling him up to interpro involvement off the bench by Xmas isn’t too much of a stretch.

If he’s really pushing on, both onfield and in-training week to week with the physical and mental load of pro-rugby, there could value in adding him to the Champions Cup squad and wider Cat 1/2 squad panels depending on the opposition and context.

With a talent like this, rushing him is as bad as stalling him if you really want him to develop. He is still growing into his senior pro frame so catastrophic injury is still a big risk at this stage of his development, especially when he’s going weapons hot against heavier, more experienced opponents that have zero regards for how he develops.

Training three days a week against the likes of Holland, Beirne, Kleyn and Snyman will give him a full examination of where he’s at athletically, technically, emotionally and intellectually but only live games at the right time will “bake in” what he learns in training.

I truly believe that, with a bit of patience, we have a top international player on our hands here. The sky is the limit for Thomas Ahern and, with a bit of luck, we’ll see him live up to that rich potential.

Up next in the Young Bucks series – Jack Crowley.