I'm just telling you what I've read. Here's another way to look at it. Here are their respective minor league numbers at the same ages:
Ramirez
2002 (18) - Rookie, A - 289 pa, 7 hr, 45 rbi, .352/.401/.548/.949
2003 (19) - A - 464 pa, 8 hr, 50 rbi, .275/.327/.403/.730
2004 (20) - A+, AA, Rookie - 428 pa, 6 hr, 46 rbi, .314/.369/.436/.804
2005 (21) - AA - 519 pa, 6 hr, 52 rbi, .271/.335/.385/.720
Bogaerts
2011 (18) - A - 296 pa, 16 hr, 45 rbi, .260/.324/.509/.834
2012 (19) - A+, AA - 532 pa, 20 hr, 81 rbi, .307/.373/.523/.896
2013 (20) - AA, AAA - 439 pa, 14 hr, 59 rbi, .298/.397/.493/.891
So to look at it by ages:
18 yrs old
Ramirez (Rookie, A) - 289 pa, 7 hr, 45 rbi, .352/.401/.548/.949
Bogaerts (A) - 296 pa, 16 hr, 45 rbi, .260/.324/.509/.834
19 yrs old
Ramirez (A) - 464 pa, 8 hr, 50 rbi, .275/.327/.403/.730
Bogaerts (A+, AA) - 532 pa, 20 hr, 81 rbi, .307/.373/.523/.896
20 yrs old
Ramirez (A+, AA, Rookie) - 428 pa, 6 hr, 46 rbi, .314/.369/.436/.804
Bogaerts (AA, AAA) - 439 pa, 14 hr, 59 rbi, .298/.397/.493/.891
So at each age, Bogaerts was playing higher up in the system than Hanley. And his overall production was greater. Hanley gets the edge as an 18-year old in production, but he was playing at a lower level then.
So looking at these numbers, we see that Bogaerts was more productive at the same respective ages than Hanley, *while playing each of those respective seasons at a higher level*.
That says to me that Bogaerts' upside is greater than Hanley's. Hanley had several spectacular years and is really gifted. Bogaerts looks like he could project to be even better.