UPDATE: Well, perhaps the NAM still takes Debby to the Texas coast; 0Z EURO has Debby making landfall in extreme S.E. Louisiana as a 985mb hurricane. Could still drag westward from there, but a significant "right hand" shift here as well.

If in fact if Debby moves N.N.E. and over N. Central Florida as it appears to be doing, I believe post analysis of model discrepancies will bare out that with this particular storm, the GFS had "better initialized" strength & position for each of its more recent runs. Therefore, if Debby were right now a more vertically developed storm and perhaps 150 miles farther to the west, perhaps Debby would now be moving more westward.