Using data on offensive linemen for recruiting classes from 2005 to 2021 (data: https://www.collegefootballdata.com/), I found a statistically significant difference between 3, 4, and 5 star categories (p < 0.001). A Shapiro-Wilk test indicated a non-normal distribution for weights (p < 0.001), therefore a Kruskal-Wallis test with pairwise comparison was conducted.
Median weight for 3-stars was 285. 4-stars was 295. 5-stars was 305. Apparently weight is a factor in the ratings process.