might help to know where you are ....

all evergreen plants lose interior leaves .. with conifers.. its on a 1 to 3 year cycle.. depending on type ...

it can be significantly impacted by transplant ... especially if dug for ball and burlap ... also by drought.. and/or a bad winter ... and even worse.. all 3 at once ... not to mention improper followup care ...

the buds are extending on yours.. and look pretty happy.. up top anyway ...

one thing newbs to conifers dont seem to get.. is that they are trees .. and they grow in tree time... we are talking about an observable impact.. in what you see.. in 3 to 5 years ... dont look at it like an annual or perennial... and expect fast quick change ...

finally ... look at the pix at the link ... IMHO ... its sited 5 to 10 feet too close to the house ... for the potential it has.. over the decades ... it appears to have been sited.. for the size it was at purchase .. but.. being a tree.. its never going to stop growing ... in your lifetime, anyway ..

double finally ... its not a xmas tree.. and it will never look like such ... try to accept it.. for what it is.. again.. look at the pix ... its an airy kinda a tree ... dont let your personal expectations ruin.. what is a really cool natural form .. [and on rereading.. i see you noted such]

ken

ps: is it in full sun.. that close to the house???

https://www.google.com/search?q=Japanese+White+Pine+Tempelhof&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiwhbu4297MAhWGNiYKHVBhAoQQ_AUICSgD&biw=906&bih=745&dpr=0.9

Yes, it has suffered from transplant shock, though is recovering ... but, as mentioned above, it's not in an ideal spot being planted near that wall. If I were you, come autumn or next spring, I'd move it to a full sun location where it can enjoy some elbow room.

Thanks everyone for your insights!

To answer some of your questions:

1) We're in Chicago, Zone 6a per the latest map.

2) The tree is actually up again the detached garage, facing a very small patch of backyard, but has a pretty much unobstructed southern exposure. Crappy chicago weather notwithstanding, it gets pretty good full sun most of the day.

3) I'm pretty sure it was planted from burlap sack, about 2 springs ago.

Another detail I left out is that our landscaper installed a drip irrigation system, and a loop from this does encircle the base of the conifer. He usually sets it at around 60-90 min every night, usually starting at the end of May through September. The tree does sit slightly mounded, and I believe has good drainage, but I've always wondered if it could be getting over-watered. Also, we've had some soil testing that showed it to be slightly alkaline, and we're in the process of getting acidification treatments for the soil. That being said, I can't figure out why the top would still look fine if the whole tree was stressed.

Short of moving the tree away from the garage, any other thoughts on how I might rehabilitate the weaker bottom 2/3 of the tree? Or, is this really just a case of "be patient'?

Thanks again!

If you're happy with its location and enough room exist for tree to develop without needing to fight for space, then leave be. How's the soil in that location, of good depth and fertility? When I plant a specimen, I leave a basin around it and water according to weather conditions, it certainly does not require nightly irrigation, even if next to a south wall. I have a bonsai style arborvitae situated in a southeast corner and it gets a good drink about once a week. I see you have daffodils and tulips planted there and when these die down avoid planting anything that would cast shade on the pine. I know some folks hiss at the thought of using fertilizer on transplants of any kind other than annuals, though with good results I always give a bit of food to anything I move, it helps with the shock and sulking.

Lower growth probably due to lack of sun at nursery,,,south side of garage , farther into summer will be in shade,,,,( sun tracts north ) it will eventually fill in , but I would move it farther out( in fall or spring),,,reposition drip line , will get enough water on it's own

ron

60 to 90 minutes a night for irrigation? We both have plenty of water in our environments but I'm five hours from you in warmer St Louis. I just water my new transplants a gallon or so if we go three days without rain. After that year I maybe water the grass once or twice a year except in drought and we did have one on 2012.