Alumni Recommendation Impact on PhD acceptance

[dontor]

Do you guys know how much a letter of recommendation from an alumni can make a difference? I applied to Stanford EE PhD and didn't receive an interview (it seems like they don't interview all their applicants who are accepted). Low GRE comparatively. GPA average.  I am a BME so it's tough already to get in with the field switch I would think. Some publications, 1 in the field, other in drug delivery not related to EE.