How much does Australian cricket believe in Pat Cummins? So much that he has been sent to England to replace Ryan Harris, when his last first-class match was two years ago and then back another two years to his previous appearance in a red-ball fixture.

That game was of course the 2011 Johannesburg Test, when Cummins was parachuted into the side for Harris of all people. He bowled like a genius in a seven-wicket performance that helped Michael Clarke's team to a dramatic victory, which squared the series and erased some of the embarrassment of being bowled out for 47 in Cape Town a week before.

It was all so long ago that the selection panel that chose Cummins for the tour consisted of Andrew Hilditch, Greg Chappell, Jamie Cox and Clarke himself - times have changed. So has Cummins' action, after injuries including stress hot spots in his heel that emerged during that Test, a torn side on his one previous visit to Lord's in 2012, and a pair of back stress fractures that have compelled the assistant coach Craig McDermott to remodel his bowling action in order to alleviate the stress placed on his now 22-year-old body.

So is Johannesburg still relevant? Cummins thinks it is. "Back then I hadn't played a first-class game for about six months and certainly the few days leading in I was really nervous," he said. "I didn't know whether I was going to swing the ball and things like that. But when I played I kind of surprised myself. Bowling now in the nets and a few centre wickets in Brisbane, I feel pretty confident.

"I haven't played a lot of red ball but I have still played a lot of Twenty20s and one-dayers and been bowling a lot. In terms of my body I feel 100% confident, the last month or so I have just been bowling with the red ball trying to rediscover swing and all those things that come with a first-class match and I have been really happy with where I am. I haven't been put in a game yet but if a game comes up I am feeling really confident."

For now Cummins is definitely behind Peter Siddle in the order of preference, but with Siddle a likely starter at Lord's ahead of the ginger Mitchell Starc, it would only take one more fast bowling injury to pit Cummins into the Investec Ashes furnace. His confidence springs from long bowling stints in India during the IPL. Cummins was a reserve paceman for Kolkata, coached by none other than Trevor Bayliss, and logged 30-40 overs a week in the nets.

"Rod said going over to India to keep bowling through the IPL and make sure you are ready to go in case anything happens," Cummins said. "During the IPL I didn't play that many games, so there was lots of net time," he said. "We would go down an hour or two before the start of play and bowl on the field for seven, eight, nine or 10 overs.

"I wanted to make sure I was bowling plenty of overs before anything did happen. There were big days and small days, probably 10 or 12 overs, anything more takes a bit too long, but when you bowl that three or four times in a week you end up bowling 30 or 40 overs in a week, which is quite a bit."

In England, Cummins now finds himself taking advice from numerous wise heads, including Harris and Mitchell Johnson, who overtook McDermott's Test wickets tally in Cardiff and is now being jokingly referred to as the "new bowling coach". Harris' counsel has been of particular value.

"It's good that he's stayed on and been around a couple of net sessions and just had a few talks about little things he's tried that works, especially over here in England where he's played beautifully," Cummins said. "Just little things, how he moves the ball and what he does and doesn't have to try and do and just little things that mean I don't have to learn on the job."

Given how little he has played, and how Cricket Australia have managed him, it is understandable that Cummins yearns for another chance in a Test match. "I love I guess the contest of backing up three, four, five days in a row and swinging the ball and building up spells," he said. "The little contests I find probably the most enjoyable."

The "little contest" Cummins now finds himself tossed into is the Ashes. There is every chance he will be needed to reprise Johannesburg before the tour is out.

Daniel Brettig is an assistant editor at ESPNcricinfo. @danbrettig