The NBA measured Jimmer at 6 feet and 3/4 inches in bare feet. He was listed on the roster as 6'2", just like Nick. However, my guess is that Nick is an even 6 feet barefooted.
Against long and athletic teams like USC, Nick has a harder time getting his shot off. Against USC he was 5-17 from the field for .294 and 3-11 from 3 for .273. Last year's offense was more wide open and Nick naturally had more open shots.
We all hope Nick will shoot better in the future, but maybe last year will be his best shooting year of his college career at 43% from the field and 38% from 3. He is shooting 38% from the field this year and 33% from 3.