I'm not a Reese fan, but she is 23rd in the W in win-shares, the 3rd highest ranking of any player on a team with a losing record, and one of only four players in the top 25 on a team with a losing record.
She's 15th in the W in defensive win-shares, the highest ranking of any player on a team with a losing record, and one of only two players in the top 25 on a team with a losing record.
I think it's a bit extreme to say she cost them 10 wins considering she's doing the most on not just her team, but just about any team with a losing record in helping her team get the few wins they've gotten.
You're right about her FG%, though. Only Brink comes close, and Brink attempts 4x as many 3's per game, so it's a bit more to be expected. Reese is 5th worst in the league at 2pt. FG% among players who attempt at least 5 FGs/game (and the only post player in the bottom 10).