wild pitch rating

I never paid much attention to this, but some pitchers have 20 wild pitch ratings, while most are in single digits. How many more wild pitches does that translate to over a season for a regular starter?

1964 - Don Drysdale WP rating: 8, 11 Wild pitches, 321 innings pitched (from Baseball Reference)
1964 - Gary Peters WP rating: 12, 15 Wild pitches, 273 innings pitched
1964 - Sandy Koufax WP rating: 9, 9 Wild pitches, 223 innings pitched

I'm guessing Strat assigns a rating based on wild pitches per 200 innings pitched.

We can make conclusions based on this sampling.

Maybe a rating of 9 means he'll throw about 9 wild pitches every 200 innings and a rating of 17 means he'll throw about 17 wild pitches every 200 innings, and a rating of 20 means he'll throw about 20 wild pitches over 200 innings.