Brachylog, 1212 9 bytes
-3 bytes thanks to Fatalize
ạ{;96-}ᵐ+100₉₆ᵐ+100
Takes input as a string of lowercase letters. Try it online!Try it online!
Explanation
ạ Convert input string to a list of ASCII codes
{ }ᵐ To that list, map this predicate:
;96-₉₆ Subtract 96 Pairfrom each charcode with 96
- and compute the difference
+ Sum the resulting list of numbers 1-26
100 Succeed if the sum is 100, fail otherwise