I've been doing a bit of thinking about our bowlers, both fitness and selection wise.
The science says bowlers under 25 years of age will have growing pains at the best of times, even with the best actions possible. McHesson don't appear to subscribe to bowler rotation in tests like Australia do/did, but are quite happy to do so in ODIs. Where everyone should agree is there is a need to have a stable of at least six test standard pace bowlers in the modern era. McHesson also appear to favour experience and not letting ability go to waste easily, both in batting and bowling.
McHesson seem content at present to run with Southee, Boult, Wagner, Bracewell and Gillespie with Anderson present as a fifth bowling option. I think it is admirable the current regime refuses to let Gillespie retire without putting in every effort to follow him around kicking him up the jacksie while screaming "you will bowl to your potential!" through a megaphone. While I like Gillespie and I think he is the third best bowler in the country at peak fitness, I don't think I would have backed him to the hilt like McHesson have. I don't think New Zealand needs him and since I subscribe to the school of the Feral Abacus, I think the responsibility lies with the player to be at his best and not with the coaching staff, which either through the fragility of his own body or through his own doing, Gillespie can't manage without having a lot of bowling under his belt first.
I also think Gillespie is a dangerous pick when he's not peaking because along with the bakery offerings, he isn't very durable himself. In a group of bowlers where the majority are in the dangerous under 25 zone, you need your back up to be both durable and able to bowl to a reasonable standard. This is where the likes of Peter Siddle and his more accomplished peer James Anderson are worth their weight in gold: they never get injured and they're good. Siddle might have less potential than a Pattinson, a Harris or a Cummins but he will play every game and is world class or approaching it in his own right. Obviously New Zealand don't have anyone who combines the Siddle qualities in one package at the moment, but fitness is something you want from your reserves. Wagner and Bracewell are probably the most durable we have, and neither have proven to be either better than their peers or consistently test standard.
I also think we should look at what balance we want from the attack and how the reserves complement it. Wagner is the designated old ball bowler but two left armers in the side open us up to creating rough for offspinners when our two best spinners are left armers. Instead I think we should run with just the one left armer and bring in Milne, who isn't noted for his old ball merits but brings the ability to swing the ball both ways at pace into the frame. The offspinner is the most common spinner in the world and we can't be giving them rough every game, especially if Anderson comes into the side which would mean three left arm pacemen. I would keep Wagner in the reserves as back up for Boult and his durability is a plus. I know Milne isn't known for staying on the park but he has a good action so I'm optimistic his injury record will improve with time. Matt Henry is another who I think will be able to remain on the park more often as time passes.
I also think the Bracewell as third seamer back of a length enforcer experiment is an abject failure. He's a pitch it up outswing bowler or nothing afaic.
My bowling squad would be:
Southee - Bracewell (fast medium outswing)
Boult - Wagner (fast medium left arm swing)
Milne - Gillespie/Henry/Butler (no real correlations since Milne is unique on the first class scene, but all of those named would make good first change bowlers and two of them have tidy actions. Gillespie only plays if he's bowling well, but if he's bowling well he is the first choice)
And I'd be looking at Wheeler, Small, Mathieson, Verma, Bennett and Bartlett as blokes who can push for future squad selection. The squad looks no more or less injury prone than it is now but that's due to the age range of our best bowlers more than anything, and they are all players who I think will only get less injury prone as they mature.