All the arcs indicate is that at a few specific times the plane was roughly at a few points along the arc, not that the plane flew exactly along the arc.
Not even that. The arcs represents the possible positions of the aircraft at the time of the last ping. This seems to be mostly based on the measured distance of the plane from the satellite and the limits on the altitude of the aircraft. This ought to yield a full circle. Consideration of satellite coverage eliminates parts of the circle, and other parts have been eliminated by consideration of the range and possible speed of the aircraft.