I see a lot of misinformation out there right now regarding his size. But Shaq Thompson is not an undersized weak side linebacker. I see many comparisons to Thomas Davis, but that isn't entirely accurate.
A better comparison that can be made physically is with the best WLB of the past two decades... Derrick Brooks.
Derrick Brooks - 6'0 - 235lbs
Shaq Thompson - 6'0 - 228lbs
Only seven pounds separate the two players physically. It would have been unwise for Thompson to bulk up before the draft, not knowing where his new team would place him.