Twell is gradually moving up as she doesn't have the basic speed (may not for the 5000m either unfortunately) to win much at the world level (CG are a second-rate meet). But she is, at this point anyway, a poster girl for doing it right (World Junior 1500m champ), and not obsessing about one event. The NCAA simply wasn't necessary for her development - her performances and progression clearly show that to be the case. It has helped Hannah England, and others - but then they weren't World Junior champions either. The WJC has helped (and/or a good agent) her get into the diamond league meets, which is both remunerative and allowing her to get into fast races.
I wonder what her real 400m speed is? the british stat site (Power of 10) says that it is 58xx! So 2.02 and 4.02 are pretty good if that is indeed a true reflection of her ability. I can see big chunks of time off her 5000m as she works on increasing her fitness. It isn't there just yet as you could tell in the race with Huddle - who dropped her easily in the last few laps.