Fergus O'Neill averages 20 with the ball, but can he play Test cricket?

It is a question of when, not if, Australia's Test attack will go through a significant transition and by every metric, Victoria's Fergus O'Neill should be perfectly placed to be part of the next phase. Every metric that is, except one.

The 24-year-old can lay claim to being the best seamer in Sheffield Shield cricket for the past two seasons. His first-class record is stunning - 134 wickets at 20.37 from 34 matches, striking at 48.4 and conceding just 2.52 runs per over. He's twice been picked for Australia A, including on the recent tour of India which shows the national selectors' respect for what he has accomplished with Victoria.

But on the eve of the new Shield season, a week after England named an Ashes touring squad with potentially their fastest-ever battery of quicks, it is very clear what metric O'Neill is perceived to be missing.

O'Neill is aware of it and he's not trying to rail against it. He knows what his strengths are but he also has a great example to follow in Victoria team-mate Scott Boland, who has shown the path of how to go from a dominant domestic bowler to a high-class Test performer without the exceptional pace that some perceive is needed.

"I think for me, the air speed thing is a little bit of a myth, not completely, but I feel like Scotty, whatever he is bowling on the gun, it feels 10kph faster," O'Neill told ESPNcricinfo.

"He's obviously still certainly fast enough, but they speak about energy on the ball and how the ball hits the bat, and I feel like, for me, I need to make sure that I still have that, and I have that for my whole spell.

"Then there's little things you need to add in here, like a little up in speed ball I've been trying to work in or a surprise bouncer.

"It's probably something that I haven't really done the last two or three years. I've just kind of come in and bowled the ball up at the stumps and tried to seam it around, and fortunately the wickets have been in my favour.

"But a day is coming where the wickets won't be in my favour, and at the next level they're certainly not quite the same. So that's where I kind of have to upskill, whether that's just a little bit more energy on it for a little bit longer, or that up in speed bouncer, a little surprise ball, because I think that's going to be the difference.

"If conditions are in my favour, I'm going to be fine. But it's when the conditions aren't in your favour, and it seems to be like they're less in your favour the higher the level you go. So it's just being able to find little ways."

He got a taste of it in India last month with Australia A, an experience he could not speak highly enough of for all that it entailed. On a surface in Lucknow that yielded just 13 wickets over four days, he ground out 19 overs for just 66 runs, the second-best economy rate of any seamer in the match and prised out India Test wicketkeeper batter Dhruv Jurel, albeit after he had compiled 140.

O'Neill said the margin for error was small. Anything overpitched or wide went to the rope, when such misses in Shield cricket can often extract a nick due to the excessive sideways movement on offer. Watching the second four-day match from the sidelines also reinforced the issue of speed.

"What I learned from being over there is, especially in India, on those pitches, ball speed holds a bit of weight," O'Neill said. "Henry Thornton was probably the main one that had some success in that second game. He just had that little bit more speed. And I don't think it necessarily has to be every ball. You've got to have an element of [going] up in speed, or an element that you can hit someone on the pad.

"Mohammed Siraj kind of did that when we were watching. It look liked for three overs he was bowling my pace. And then for three overs he decided to really ramp it up and crack in. "So it's interesting. I think it goes to show how good the Aussie boys are. Whether they're playing on a flat wicket like that in 40-degree heat in India, or they're playing on a green seaming wicket somewhere in England or South Africa, they're certainly well-equipped wherever they go."

O'Neill will never match the physical capabilities of Australia's big three. But he is following Boland's advice on strength training and doing some minor technical things to create an "up speed" ball.

He is also a victim of his own success. His Victoria coach Chris Rogers calls him a captain's dream because he can lock in for long spells without fail and says "he never lets you down". But O'Neill thinks he could play a different role if conditions asked for it.

"Another one is probably effort," O'Neill said. "Some of these games that I've played, I've just bowled seven overs in a row and just kind of dawdled in and gone about my business, and that's been good enough. But if you're going to go somewhere else, it might be four overs at a bit higher intensity, a bit more effort. It's all things I've got to figure out. But certainly by maybe making some technical tweaks, biomechanically, and then adding physical attributes, improving that is not going to do me any harm."

Rogers, with five Test centuries to his name opening the batting for Australia, knows what great Test bowling looks like and he thinks O'Neill can perform at that level without necessarily needing to add any speed.

Rogers referenced two former opponents in Mohammad Abbas, who in a neat convergence of styles followed O'Neill at Nottinghamshire in the recent County Championship season, and Vernon Philander as great models for O'Neill, who were both unrelenting in their accuracy.

"Mohammad Abbas at his best, he never missed," Rogers told ESPNcricinfo. "Probably the better reference point is Vernon Philander. I think that's his model. He's still a relatively young man. When he gets to his absolute peak, if you put conditions in his favour, he'll absolutely strangle sides.

"That's his challenge because his skill level is exceptional and he's a little bit of a point of difference to everyone else that's going around. And certainly I think he'd do a really good job if he got picked for Australia, particularly in the right conditions."

Those conditions may present themselves in 2026 and 2027 when Australia tour South Africa and England. O'Neill has already built his away Ashes case with 21 wickets at 17.90 with two five wicket hauls in his four-game early-season stint with Nottinghamshire this year and is set to head back to Trent Bridge for a longer stay next summer to try and help the county win back-to-back titles.

"It was so much fun," O'Neill said. "I learnt that I like the Dukes ball a bit more than the Kookaburra, and certainly a lot more than the SG."

But with the fitness of Pat Cummins currently under question and the age and injury history of Boland and Josh Hazlewood, there may be spots up for grabs in this summer's Ashes series.

Where Australia turn beyond the big four is a major talking point, with Brendan Doggett to miss the opening Shield round with a hamstring niggle having missed the tour of the Caribbean with a hip problem. Jhye Richardson and Lance Morris are injured. Michael Neser is 35 coming off a significant hamstring injury last summer.

Rogers believes O'Neill should be seriously considered if injuries occur.

"Yeah, I do. He will challenge the top of the stumps," Rogers said. "And, yes, England might attack him. But that means they are going to have to take a lot of risks. At least he'll say if you're going to hit me, you've got to hit my best ball and then that hopefully will create chances."

O'Neill has a different focus coming into the summer, parking the desire to play at the highest level and instead focusing on the task at hand with Victoria as they chase an elusive Shield title that has been within reach over the past three years.

"My desire is to win," O'Neill said. "That's my main objective. I don't really look to get too far ahead. I think Baz [Boland] is a good example of that. Just keep putting your head down and keep going about your work. And if the timing's right, it'll happen.

"I think there's a lot of players that you could make an argument for to come in if there's an injury. A lot of players who have had a lot of success for longer than me. So maybe they will get to go first. Maybe they don't, who knows. But I'm not worried about that. I'm just looking to play and win this first game at Adelaide Oval.

"Knock off the champions, South Australia, and then get the ball rolling."