The 2014 title you refer to, DT's opponent was a 15-19 Chicago Sky team and the Mercury were up 2-0. DT made great plays and hit the clutch shot but it was far from a 1 woman show....even without Griner that game, the roster had Candice Dupree (who scored 24 that game), and Dewanna Bonner. And again, the opponent was flat out not very good while Phoenix was fantastic that year.
The article highlights how important Catchings was to her team's success, perhaps more than anyone else in the league's history. I personally dont think it makes her the best ever, but it is a valid argument the writer tries to make.
I know people have varying opinions on best WNBA player, but I don't think there is a cut and dry answer. On the men's side, it is almost universally Lebron or Jordan with some people throwing in other names like Russell, Kareem, and Kobe. On the women's side you can make really compelling cases for any of Cooper, Leslie, Swoopes, Jackson, Taurasi, or Moore. Plus you can throw in Catchings, Parker and Bird on the periphery.