An oscillating sprinkler is the worst way to water. Put a hose next to the trunk on a slow trickle and leave it for 30 minutes or so until the rootball is fully hydrated.

tj

and i hope there isnt fabric under the stone...

and i wonder if its planted at the proper depth ...

pull back the rock.. and look for the root flare ... take a pic or two for us ...

https://duckduckgo.com/?t=ffsb&q=tree+root+flare&iax=images&ia=images

then take a hand trowel and dig a couple holes.. in the gob planted.. and in surrounding soil .... and FIND OUT about moisture at root depth .. and water accordingly ...

i also suspect severe under watering... thru the root mass planted .... i would also... after the holes are dug.. probably putting the hose on trickle... until there is water 3 to 6 inches down ... dig more holes and find out ...

and then dont water again.. until it is drying down int eh root mass... dig more holes.. no one can really tell you how it works in your soil.. in your yard.. in your weather.. so all you are left with is digging holes.. until you learn ...

only caveat.. is if you have bad non draining clay ... let us know ...

if you perfect watering.. the tree might be able to releaf and move on ...

a transplanted tree of that size.. you are responsible for ALL watering this year .. as it grows a good root mass ... in drought next year.. and then after that.. it should be rather free range.. and most likely happy with whatever water you put on the lawn ...

ken