From the description in the Monster Manual, one can clearly see the Saber-Toothed Tiger has a Proficiency Bonus of +2.
She has +3 in Perception which is 2 + her Wis modifier (+1).
She has +6 for Stealth, that means she has expertise, so double her proficiency (2 × 2 = 4) + her Dex modifier (+2).
She has a +6 to hit with both her Bite and Claw attack, that is 2 + her Str modifier (+4).
And then she has a static bonus of +5 to her damage rolls which, subtracting her Str modifier of +4, leaves us with a 1.
So I was trying to figure out what might be the case, and there's only 2 options I could think of: she either adds half her proficiency, or half her Dex modifier, per the effects of a hidden feature I can't for the love of me find.
Anyone care to help me find the consistency?