If you expect WPA to be an all-encompassing stat that tells you if a player is "good" or not, well, that's pushing it beyond what it was designed for. However, Baseball-reference.com has something right next to the WPA display, that you may like. It shows an "average leverage index" (ALI), which reflects the "blowout" effect you are geting at, and then next to that is WPA/LI, which is not simply the ratio of two numbers but is the sum of a lot of little ratios for each plate appearance. This sounds in the spirit of what you were describing. Here is the table ("Team Win Probability") for batters and pitchers, respectively, on the 2019 Twins: https://www.baseball-reference.com/teams/MIN/2019-batting.shtml#all_players_win_probability_batting https://www.baseball-reference.com/teams/MIN/2019-pitching.shtml#all_players_win_probability_pitching