I haven't watched enough USWNT to say how well she fits into their system or measures up to the current midfield, but she has been overall excellent at Boston and is a perfect fit for the system Patao is building; a possession/press style of play. I think a lot of people overlook her contributions to the team and their more recent successes at controlling the midfield as the season has gone on - even against top-ranked teams in the league.
I think a more defensive-minded midfielder is an easy to overlook position as you tend not to end up on the scoresheet a lot or make flashy plays that end up in highlight videos. However, she is incredibly talented on the defensive side of the ball at knowing exactly where to be to clog up passing lanes and when to step in for a tackle/interception. On the offensive side of the ball, she is extremely good at maintaining possession under pressure. She somehow always manages to squeak a pass out to a teammate as defenders are swarming around her. This aspect of her play reminds me of watching Busquets always evading the press.
If I had a criticism of her play, it would be that she can sometimes struggle to transition from defense to offense. She is so good at defensive positioning, that I find she will kind of do it on autopilot even after Boston has taken possession. She could do a better job of releasing and finding space to more cleanly receive a pass and/or relieve pressure on our front line.
I would love to see her on the USWNT. Reale is the only US call-up that Boston had in the most recent break, but she didn't have any actual minutes in the two games against Spain. Maybe someday a Boston player will get a US cap, and if I had to guess who is most likely, it would be Karich.