Coaches tend to develop their own idiosyncratic systems, but “Sam,” “Mike,” and “Will” have, since the 1990s, become accepted by most teams playing 4-3 defense (“Mike” is sometimes called “Mack”). The names have even found their way onto some teams’ official Web pages listing player positions. But what happens if, say, first-year New England Patriots linebacker Mike Rivera isn’t a “Mike,” but a “Sam” or a “Will”? A return to the days of Sarah, Meg, and Wanda would solve that problem. But in football these days, masculinity comes at the price of a little ambiguity.