Afraid I mostly agree with the rest! The backs don't look good at all, but perhaps that's a comparitive statement, based on how they were when you got him? I don't think there's enough to go on by far, to jump to conclusions about the competency or otherwise of the farrier though. Perhaps this is a new farrier for him, so don't know what he started with either, but it does appear, IMO, he could do better with the back feet at least. From what can be seen(need more to really know), the fronts don't look too bad though(trim-wise) so perhaps the shoes are the only reason the backs are so different. Seeing some sole & other angle pics would be helpful - see my signature link for more info. Now here's what I see...
Firstly, I am assuming the lumpiness is just mud?? I know it may be difficult, but for best critique pix, hooves should be clean. It appears on the back feet at least, that the farrier has rasped the surface of the wall quite a way up? Did the horse have substantially more flared toes before he trimmed them? How about the fronts? It may be just disguised by mud but it appears that he didn't rasp the wall surface of the front feet? Were they in substantially better shape to begin with?
All feet are flared, the fronts perhaps only at the toe, but you can see the difference in angle in the top half inch or so(month??) of growth, that it has changed & appears to be growing well attached there. In the front lateral pic I marked a red line, showing about where I imagine they 'want' to be. You'll notice the line above the hairline, which I did to illustrate the possibility(again, not sure at all with only these pics) of a broken forward pastern axis. The wavy line of the opposite foot inside quarter shows that there is imbalance & likely too much pressure at that quarter, which may be remedied by 'scooping' the quarters, as per whatever the sole plane dictates.
Regarding growing out separation, I don't like the idea of just rasping flares off from the wall surface - this is mainly just cosmetic and may also remove too much wall strength and also protection for the front of the foot. I would instead do it in a similar way that he appears to have addressed the fronts - by bevelling/rolling the toe back from underneath(without trimming into sole!). This removes the load & leverage from the disconnected wall, to *allow* the disconnection to grow out. The fronts may or may not need to be bevelled more - can't tell from those pics of hoof in grass, but the lateral pic of his back foot that I marked hopefully illustrates what I mean better. In that pic, the straight blue line is about where I imagine his hoof 'wants' to be and the curved blue line at the bottom is around where I might trim it, to allow the flare to grow out. For the sake of cosmetics &/or interference I may also 'dub' the toe as he has done, but would only go about 1/3 of the way up the wall max, if that much, to preserve as much wall/protection as possible.
In the front-on pics of his backs it is clear the flaring is all the way round, not just at the toe, and I would basically address it in the same manner - bevel/roll the walls from the ground surface, to wherever the ideal 'hoofprint' or 'breakover' should be for him. Regarding finding what is correct for him, I think Equine Lameness Prevention Organization
describes the hows & whys quite well.
Regarding the crack, I disagree that shoes are a good idea, because you're just peripherally loading already disconnected, fractured walls, for one. I think the best treatment is to *releive* pressure, not put more on the walls. So for a number of reasons I'd ditch the shoes asap, but of course, that's another something that you'll have to do your own research & make your own decision on. Hopefully my signature links will help you start learning, to enable you to make objective decisions.
In the back lateral pic, I've marked in red approximately where I may further roll/bevel the wall to releive that crack more. Tho that may not be needed at all, if the foot can be otherwise well balanced & disconnected walls releived sufficiently. I would also suspect that infection in that crack is very likely, and that would also be perpetuating it, even when the hoof is well balanced. I would definitely be treating it seriously and would also seriously consider digging it out/resecting may be a good move.
Other things... Diet is SOOO important for hoof health, which I don't know if that's stating the obvious to you or not, but check out Katy Watts | Safergrass.org
for starters, if you haven't already.
That right rear heel looks like it's suffered a pretty major 'blow out'. I'd keep tabs on that, to avoid/treat further infection. Also with that much separation & probably weak heels, he will likely need protection for the base of his feet, when being ridden on hard ground at least, so I'd consider hoof boots.
On average, 5-6 weekly is a reasonable schedule IMO for trimming/shoeing. I would not leave shoes on for more than 6 weeks max, but for just trimming, some horses can healthily go a bit over that. However, many horses need more frequent trims - 3-4 weeks - and I think it's especially important in treating unhealthy hooves, to do them more frequently, in order to *keep* them in shape & improving, rather than allowing them to get further out of shape before 'correcting' the imbalances. Therefore(another 'con' of shoes IMO), with feet such as his, I'd be inclined to do little & often - say fortnightly. If your farrier's a decent type
he may be willing to give you an old rasp & instruct you in doing interim trims to keep him 'touched up', so that you don't have to get the farrier more than 6-weekly.
So anyway, that's my take on it. Hope it helps & I'd be interested to see/hear more. Cheers!