The difference in the “weed out” environment is that a perfectly respectable 3.0 GPA in frosh year means that the student will be weeded out of mechanical engineering at Penn State (3.2 GPA required) and may or may not get weeded out at Purdue and NCSU (ask mechanical engineering departments to find out more about the actual thresholds, since it is not explicitly stated on the web sites), but will be allowed to major in mechanical engineering at Pittsburgh.
Frosh year is usually the riskiest year GPA wise, since the student needs to adjust to college work compared to high school work. Students commonly improve their GPAs in later years.