As others have mentioned, lower light indoor action photography is one of the toughest - some very skilled photographers still fail at this type of photography, because though they are good, they don't have the experience in shooting this type of subject.
Shutter speed is indeed key, and actually 1/400 might be acceptable, though probably at the very lowest end of what shutter speed would be needed - 1/500 to 1/2000 would be more like it. Other factors too could have been the lens - what lens was it, what was the focal length, and was it stabilized? Blur could be from the moving subject, but also could be overall softness or blur on a long lens where camera shake came into play...a 400mm lens at 1/400 would be the very edge of stable for a photographer with a good stance, so a less skilled one might struggle more.
To get the shutter speed, you need big apertures and high ISOs unless the light is perfect and bright direct sun. What might seem like reasonable indoor lighting to your eye might not be so to a camera sporting a slowish F5.6 - 6.3 aperture lens. As much as some folks like to avoid high ISO, there are sometimes no substitutes, and cranking up over 1600, maybe even 3200, might be needed to get the shot. Your camera should be capable if properly exposed of shooting something quite decent at ISO3200.
So many other variables need to be considered though - white balance can be tricky indoors, good panning technique can help keep the subject nicely in focus and motion-blur free, while letting the background blur a little to imply motion. The right focus mode is crucial - is the multi-point focus system able to properly pick out the subject, or are other things interfering or stealing focus? If so, switch to center or spot. The right metering mode is crucial - if in S, A, or P mode, if the metering is too wide, the camera can overexpose, also selecting too slow a shutter speed if too much of the scene has dark objects in it - if spot metering, it might try to meter off far too small a section and through off the metering and aperture/shutter selection from shot to shot. Was the focus in continuous or servo mode? if yes, keeping the focus point on the subject is crucial, otherwise it could all go wrong. If it was in single AF mode, was the shutter half-pressed first to acquire focus? If so, the subject may have moved before the shot was fired. Was any pre-focus technique used to anticipate the subject's location in advance to shorten the AF acquire time? Was the camera in continuous frame/burst mode or firing single frames?
So much to consider - and even with everything done right, the lighting may have been too challenging for the settings or for the lens used. Much skill is needed to know instinctively that there will be a problem and adjusting for it, so there's no reason for her to feel bad - some very good pro photographers I know still probably wouldn't have done any better because that type of shooting isn't their forte.
Sony DSLR-A68 / Sony 18-250mm / Minolta 50mm F1.7 / Tamron 150-600mm / Minolta 300mm F4 APO
Sony A6300 / 18-55mm F3.5-5.6 / 55-210mm F4-6.3 / 10-18mm F4 / 35mm F1.8 / 16mm F2.8 / FE70-200mm F4 G OSS / FE70-300mm F4.5-5.6 G OSS / via manual adapter, lots of Pentax K mount, Konica K/AR mount, and Leica M mount manual lenses