Even though the FMS website does not share any criteria regarding past experiences but in the final merit list for admission they give 10% weightage each for marks obtained in class X and class XII. Along with this, they also give 5% weightage to Extempore, 15% weightage to Personal Interview, and 20% weightage to Group Discussion.
You may do very well in the 90% of the final merit list criteria but the 10% past academic performance is where you face the final heat and students who have scored exceptionally well have a higher chance to convert a seat in FMS Delhi.