Just making sure I'm not crazy

I am thinking of changing my (1000lb 7yo QH Gelding) horse's diet a little. When I bought him last October, he was kind of rough looking- a bit underweight, coat a little dull, etc, but nothing horrible. Since then, he's been getting nearly free choice coastal/bermuda hay (eats about 20-25lbs/day) and about 4lbs of Strategy GX a day. Over the winter he was also getting a couple lbs of alfalfa pellets and a 1c veggie oil daily.

Since then he has put on a lot of muscle, grown in a nice coat and is up to the weight I want him at. He works 5 days a week, typically an hour or so, though longer on weekends. We are stepping it up and he's doing a lot more canter and trot work in the past month. He is stiff occasionally, barely noticeable, but warms out of it and can be a little sensitive on gravel (barefoot). His right hock and fetlock pop when I do his feet and his farrier's commented that he's a little stiff in the shoulders.

I want to keep him on free choice hay (nice coastal, tested 15% protein, better than what I had over the winter) because I think it's important for their minds and their stomachs. I want to cut out the Strategy and switch to a ration balancer. I have also added in a joint supplement in the past couple of weeks as maybe a treatment for the stiffness, but more as a protective measure.

Does this sound like a reasonable plan? This is my first and only horse, so sometimes I just need a little hand-holding and assurance that I'm not doing something that will negatively impact his health or soundness. Or a heads up if it will. ;)

Sounds like a good move to me, to cut out the starchy/sugary strategy & also add something that will give him balanced nutrition.

Re the cup of oil, that seems like a lot for a start, but it's also extra important to build up to whatever amount you feed over a couple of weeks and feed it little & often, not in only 1-2 feeds per day if you're feeding oil, because horses don't naturally have the enzymes to digest it.

I agree it sounds like you're moving in the right direction.

One thing that sticks out to me is the 15% protein of your hay. We don't get coastal in my area, but I think that's a grass hay if I'm not mistaken? 15% is very high for grass hay- more like what I'd expect for the lower end of alfalfa hay (based on this publication), so you might consider matching it with a ration balancer designed to be fed with alfalfa.

Most brands make a formula to be fed with grass hay and a formula to be fed with alfalfa. Not sure which brand you're feeding, but here's a handy reference chart: Specific Ration Balancer Products