They're really not and I'm fairly sure I've explained this to you before but I'll do it again. If you want to make the suggestion that Baez and Rizzo's first stint have similar batting average then fine. That's a perfectly fair statement. However, if you go so far as to say their overall statistics are "very similar" it leads me to believe you don't understand their representation.
Let's start with walk rate. In 153 PAs, Rizzo walked 13.7% of the time or 21 times. I don't think I need to explain why walks are a good thing. But I will go so far as to suggest that walks are often a indication of a good hitter. Obviously they aren't the only thing but if you're walking about 10% you generally have a shot to be a useful player. Case in point, Valbuena hit .218 last year but with a 13.6% walk rate and decent defense was around a 2 fWAR player. Conversely, Baez has walked 12 times in 187 PAs(6.4%). That's not even league average which is 7.7%. For some perspective, over the past 4 years a 6.4% walk rate would put him at tied for 69th worst out of 283 qualified hitters. At 13.7% Rizzo would have bee 8th best on that list. Clearly that number normalizes some over more at bats but the point here being that there is a vast difference between the two.
Now let's go to k's. At 30.1% Rizzo's numbers were high. However, Baez at 41.7% is 2/5th's higher. That's significant. And even if you make the argument that Baez drops his current k rate the 10.8% Rizzo has to his career K rate, that means Baez would be at a 30.9% clip. Over the past 4 seasons only 8 players have K'd at that rate. Chris Carter in 2013(36.2% 0.4 fWAR), 2012 Adam Dunn(34.2% 1.8 fWAR), 2014 Chris Davis(33% 0.4 fWAR), 2013 Mike Nappoli(32.4% 3.9 fWAR), 2013 Dan Uggla(31.8% 0.4 fWAR), 2011 Mark Reynolds(31.6% -0.1 fWAR), 2014 Chris Carter(31.4% 2.0 fWAR), and 2013 Adam Dunn(31.1% -0.2 fWAR). The worst walk rate any of those players had is Chris Carter this year at 9.7% with the second worse being Chris Davis this year at 11.4%. And of those players, WAR suggest that most of them save for Nappoli(12.6% bb rate) were below league average(2 fWAR). I know some don't buy the concept of WAR but even if you ignore that to suggest he's at a similar level to those players would be a fairly massive disappointment in most fans eyes I'd imagine. Additionally, I'm not even sure you can consider him in a similar light given he's not likely to walk any where near as high as those players.
Now on to BABIP. Rizzo's BABIP in 2011 was .210. That's 50 points less than his disappointing 2013 campaign. Given league average is usually .300ish and given in his 2 good years of 2012 and 2014 he's bee at .310 and .298 it seems pretty clear that a lot of his issues were him hitting it where people were. Call that bad luck or whatever you want but as I suggested in regard to his 2013 BABIP as that normalizes his average will come up. On the contrary, Baez's BABIP sits at .253 currently. That's low but not low enough to explain away a .178 batting average. If you give him the .300 BABIP benefit of the doubt that puts him at a .226 average. If you push Rizzo's average up to .300 BABIP he'd also have been a .231 hitter but rather than a .282 on base Baez would have instead Rizzo would have had .371 on base. Again, 89 point points of on base is significant.
If you look at batted ball data, that too favors Rizzo's 2011 season. His line drive rate is 13.4% vs 12.6% for Baez. His infield fly ball rate was 5.6% vs an astronomical 21.4% for Baez. To put that into perspective, only 2 players in the past 3+ years have had over 20% and that was Gordon Beckham in 2011(21.0%) and Chris young also in 2011(20.5%). Unsurprisingly, one good area for Baez is his HR/FB at 21.4% vs 2.8% rate for Rizzo. To add to this, if you look at plate discipline data, it shows Rizzo had a 34.7% at swinging at pitches outside of the zone vs 41.9% for Baez. Rizzo had a 66.1% rate at pitches in the zone vs 56.9% for Baez. To add to this, Baez's O-Contact% which is contact on pitches outside the zone was 41.3% vs 50.0% for Rizzo. They have basically identical rates inside the zone on contact.
If you put that batted ball data together with his plate discipline data as well as what you can easily see watching the games it tells you that Baez is much more of a free swinger. In particular, the fact he's popping so many pitches up tells you along with his lower line drive rate and high O-swing% that his pitch selection is pretty poor. Unsurprisingly, when he has connected with pitches he's hitting a lot of homers. While that may seem like a positive, I think in his case it may be reinforcing him in a negative way. Put another way, he's being reward occasionally for his poor plate discipline and all out swing.
Either way, you can draw your own conclusions going forward on Baez but to suggest that Baez and Rizzo's first stint is similar is ignorant of the data. Rizzo was already a far more controlled hitter in 2011. He took walks. He had a very high Z-Swing% rate and a relatively low O-Swing%. Both of these were in line with his career line currently. Rizzo's flaws were arguably his contact rate(10% less than his career rate), his line drive rate which is likely tied in with his contact(7% below his career rate) and his HR/FB rate which again see contact(12% below career rate). Put another way, Rizzo had a good approach and got poor results. I don't profess to be a hitting coach but my guess is he likely had mechanical flaw in his swing or didn't know how to handle certain pitches and that allowed pitchers to exploit him and thus draw poor contact.
On the contrary, Baez thus far isn't approaching at bats well. He's getting himself out by chasing pitches outside the zone. In that regard he's an immature hitter. What makes me doubt Baez is that type of immaturity is often very difficult for players to overcome because they got the majors doing this and to vastly change your approach isn't easy. Even players who've had success after these sort of numbers typically take several years. Jose Bautista in particular comes to mind because his first major league season had a similar K rate and walk rate to Baez. He didn't become an above average player(2+ fWAR) until he was 29.
These are statistically similar players to Baez. Outside of Bo Jackson, Gorman Thomas and what now appears to be a flukey 2013 for Chris Davis, there isn't a lot of promise there. They all have been replacement level players and that 60+ years of data.
In summary, if people want to believe in Baez going forward that's fine. I think that it's overly optimistic but that's people's right. However, please let's stop acting like this year in the majors is some how a positive for Baez. Obviously the expectation was at least some struggle but I don't think there's anything he's done to show improvement(yet) which was the general idea behind the struggle. Also, let's not compare him to Rizzo for crying out loud. For one, they aren't even remotely similar as I've shown and for two the implication is that struggle and then finally success is the norm when in fact the norm is typically struggle and wash out entirely. Rizzo, and most other major league players, is an exception not the norm. This belief is self serving at its finest which is ironic considering the cubs prospects in general over the past 10 years. I get that to some extent that's what being a fan is but there needs to be at least some objectiveness here. Usually, a player struggling in his first stint in the majors means he's a bad player. Occasionally, it's just growing pains. As of right now, Baez has done nothing to show he belongs in the second group and to suggest otherwise is incredibly naive.