The Phoenix (14-11, 6-6 Horizon League) set season lows for points allowed and opponent's field goal percentage at 27 percent (18-of-65) in sweeping the season series against Youngstown State (10-15, 5-8).
The Penguins were held under 50 points in both meetings.
The Penguins' Quin Humphrey, the second-leading scorer at 18.7 points per game in league play, grabbed 12 rebounds but was held to a season-low six points on 2-of-13 shooting.
Schachtner was 6-of-9 from the field and scored 14 of his 21 in the first half as Green Bay took a 28-23 edge at the break. Schachtner topped 20 points for the third straight game.
Evanochko and Schachtner finished a combined 14-of-28 from the field, which was good enough to overcome a 2-for-19 combined shooting effort from Green Bay's other three starters.
The Phoenix never trailed after halftime, but it wasn't until Troy Cotton's 3-pointer with 3:38 left that Green Bay built its first double-digit lead of the game.