What is meant by NFA size is linear in the number of characters in the patternset is that there exists constants $A,B$ such that every pattern of length $n$ is accepted by some NFA of size at most $An+B$. This is proved by structural induction on the patternset, and is a rather straightforward exercise.
Without knowing the constants $A,B$, you can't predict what the general claim gives you for any particular pattern. If you work out the proof, you will get values for $A,B$, and then you will be able to obtain a bound on the NFA size for your sample pattern; that bound probably would be worse than $4$. DFA size could be much bigger. For example, for an alphabet of size $n$, the set of all words not containing all characters has a description of size $O(n^2)$, but has DFA size $2^n$ (NFA size is $n$ or $n+1$, depending on the definition).