Personal
- Parents are Mike and Maleen Nielsen
- Father pitched for BYU 1990-92 and 1995
- Brother Michael and cousins Nate and Matt Favero play for BYU baseball
Before BYU
- Prepped at James Madison High where he was coached by Mark Gjormand
- Three-time first-team all-conference and all-region, and first-team All-Met
- Team was 2015 6A Virginia State Champions
- As a junior he hit .410 with 11 doubles, two home runs, 26 RBI and scored 36 runs, with 28 walks and stole nine bases
- As a junior he was 3-1 as a pitcher, earning wins in relief in the regional semifinals and in the state final
- Lettered four times in baseball
- Names to All-Madison team featuring five best athletes in school
- Recruited by the University of Virginia and Clemson