I don't think Hader would have ever made a great starter and I think the Strider comp is ridiculous. Strider has better physical build, holds FB velo better, has better command, and his slider is actually good. Hader's slider was effective because everyone was just so locked into his FB not because his slider was actually good. Even today his slider still isn't a very good pitch because he can't consistently locate it.
Just look at the difference between Strider's slider heat map this year (on left) and Hader's slider heat map this year (on right)