Couple of observations. OP sounds to be located in the US. Thus, he will not have access to Pinnacle. It sounds like he uses 5dimes. While I have doubts as many do here, I would like to look at his statements and others' from a neutral standpoint.
1) 5dimes bans users who win a ton. Like 20k+. It sounds like this is side income to you and you do not wager large amounts. If your story is true, your unit amounts cannot be that large (or 5dimes would have kicked you by now).
2) 5dimes is not as sharp as Pinnacle. Many books follow Pinny movement mainly.
3) @danshan his ROI metric, if true, is likely his ending $ balance compared to starting balance of beginning of season. For example, 164% ROI, he finished with $26,400 from an initial $10,000 (hypothetical). Your ROI metric is the ROI per wager.
4) Just because someone does not beat closing lines initially does not mean they are not sharp. Yes, it is much more against them but all sharps started as being viewed as a rec bettor until proven otherwise. His "7 years" though is clearly a long enough period for being labeled as such.
5) Danshan you view closing lines as being the true odds. However, as we recently discussed, market makers were seeing 7-15% ROI on bets in Fairlay last 6 weeks. Obviously a somewhat small sample, but 7-15% is above expectation. This implies the public is heavier on losing sides or it could be argued the lines, such as a popular team such as the dodgers, is juiced more than the other side?
I consider myself smart in certain sports but do not have a model I use on my own. I look at several analytics though. Even though I have extreme doubts about this user's claim, I am enjoying the conversation between sharps in this thread.