Likely the rootball isn't getting sufficient water.
To determine if that's true, feel the soil of the original root ball.

Thank you for the reply. I'll definitely check again tomorrow. I feel like I've been very diligent about watering both the boxwood and the Rhododendron. I was actually concerned that I might have over-watered and rotted the roots.

I'll report back tomorrow.

When you do water, put the hose end near the main stem and adjust the water to a trickle. Let it run until the leaves perk up. This can take anywhere from a half hour to several hours (unlikely for a plant this size). You want to wet the root ball without saturating the surrounding soil. Saturation just makes things worse.

If the rhododendron was in full sun when the picture was taken, you may be seeing a natural response. The leaves look a bit droopy, but they don't seem to curling into the tube shape typical of water stressed rhododendrons. All new growth needs time to harden and it's perfectly normal for it to droop, especially in a lot of sun, until it does.

If the root ball ever dried out, it is almost impossible to get it to accept moisture again without digging it up and soaking it. I would did it up and make sure of 2 things. 1) The roots must be opened up. 2) If the portion that was in the container is dry, soak it. When the plant is dug up, don't let it get dry, If the roots get dry, the plant will die. Rarefind Nursery has excellent directions on planting container rhododendrons.

When watering, it is best to soak thoroughly and then wait until the plants shows some wilting in the morning, then soak thoroughly again. Wilting in the heat of the day is normal.

Again, watering too often is worse than letting it get dry.

Here is a link that might be useful: How To Plant (Rarefind Nursery)

Thank you for the response. I dug up the rhodo today, soaked it thoroughly and tried to loosen the roots which are very tightly bound. Unfortunately I neglected to read the Rarefind Nursery information that you suggested prior to replanting it. I don't think I did enough to loosen the roots and am considering taking it back up tomorrow and exerting some more force in loosening them as the article suggested. I feel like I have nothing to lose at this point. I'll reply back once I determine the fate of the plant. Thanks a lot.

Thank you for the response. I dug up the rhodo today, soaked it thoroughly and tried to loosen the roots which are very tightly bound. Unfortunately I neglected to read the Rarefind Nursery information that you suggested prior to replanting it. I don't think I did enough to loosen the roots and am considering taking it back up tomorrow and exerting some more force in loosening them as the article suggested. I feel like I have nothing to lose at this point. I'll reply back once I determine the fate of the plant. Thanks a lot.