The twelfth most common surname in North America is "Thomas." That's as a last/family name. The thing about "Thomas" is that it's also the tenth most common male
first (given) name, and as such, also a pretty damn common
middle name, though there aren't any obvious and relaiable statistics on that last point.
Speaking of points, the point here is that while there have been 38 big-league ballplayers -- the same number of instances the #11 name Anderson had, just as the #9 and #10 names, Moore and Taylor, each had exactly 47 apiece -- there have been far more with that appellation as a first or middle name.
In fact, even if you count only players who have been inducted into the Hall of Fame or made an All-Star team (thus ignoring virtually every first/middle-named Thomas who played before 1933), there have been 26 with the first name Thomas and 21 more with that middle name.
Perhaps here we should engage in a bit of, er, Thomistic clarification ...