William,
The problem is that the data is imported as strings.
Part[data2, 2, 2, 2, 2, 1] // InputForm
(* {"--", "Max Scherzer", "WSH", "SP", "$42,142,857", "7 (2015-21)", "$210,000,000", "$30,000,000"} *)
To convert to numbers, remove the $ and , and then ToExpression
data = Part[data2, 2, 2, 2, 2, All, 7] //
StringReplace[{"$" -> "", "," -> ""}] // Map[ToExpression];
Compute mean
N@Mean[data]
