While the individual articles covered by the umpires task force may already have importance ratings given by WikiProject Baseball, they can also be given importance ratings specific to this task force based on the following criteria:
Top Importance: Hall of Fame umpires
High Importance: Current full-time umpires, such as those listed here:
Mid Importance: Former umpires with sizable time (at least ten years) in the Major Leagues, current minor-league call-up umpires
Low Importance: Former short-time Major League umpires or minor league umpires
Also, an article could temporarily have a higher importance than usual if it has been the target of frequent vandalism or the subject of the article has had significant media coverage.
As a general rule of thumb when you cannot determine importance based on these criteria, an article on an umpire in the task force will be more important than an article on an umpire in the WikiProject. So if an umpire is mid importance to WikiProject Baseball, the umpire is likely to be high importance for the task force.
If, after consulting this, you are still not sure what rating to assess to a specific article, or if there is a dispute about the rating, please discuss it on the task force talk page.