How am I putting words in your mouth? You're the one that initially said our rotation would be lucky to be better than bottom 10, and then when presented with the projections indicating a baseline expectation otherwise are like, "projections suck". Which is for all intents and purposes saying your opinion of our rotation is more reliable.
No they're not perfect (this is statistically impossible btw), but they're by far the best of anything else that's out there. There's a reason why teams use them. Interestingly, what you want them to do, namely, account for random variance, would actually make them less accurate. I recommend these articles for a detailed explanation.
https://fivethirtyeight.com/features/the-imperfect-pursuit-of-a-perfect-baseball-forecast/
https://www.espn.com/fantasy/baseball/story/_/page/mlbdk2k15_projectionstalk/how-fantasy-baseball-projections-calculated-how-best-use-them