I know this is a troll thread, but if Baker somehow won the nomination without changing his views, he'd probably lose states like GA and NC. This will never happen, though. A Republican like Charlie Baker isn't going to win a presidential election any time soon.
I don't know if you've seen how rabid the GOP base actually is, but the fact that Ted Cruz and Donald Trump got over 70% of the vote (and people like Ben Carson also got non-negligible support) should tell you all you need to know about the chances Charlie Baker would have of ever winning a non-Massachusetts Republican primary.
I think he'd win more than the MA primary, though not many and depending on the details of the field. I'm guessing you're more or less equating him with Kasich (who won just his home state of OH), but I don't think that's a valid comparison. Two factors worked against Kasich: 1) He was not the clear establishment favorite at ANY point in the primaries (as McCain emerged to be and as Romney emerged to be), so he could neither coalesce moderate voters (who are still a significant portion of the electorate) nor financial support from donors. 2) Trump served as a catch-all candidate for anyone upset with the way Republican politicians were performing in office, and that frustration came from people of varying ideologies with a lot of different things they were mad about. You could have someone like Fuzzy Bear, who often voted for Democrats, finally finding a "populist" enough Republican, or you could have someone like my dad who was pissed that the GOPers in Congress were compromising with Democrats on budget issues/not taking a stand and wanted fresh blood. Those two voters are HARDLY in agreement on the issues, and both broke for Trump. I'm still of the opinion that Trump's appeal was not to a specific (and more importantly lasting) voting bloc in the GOP, and it remains to be seen if a future candidate can repeat that performance ... there's only one Donald Trump, as he would gladly let you know.
I think Baker would likely win VT, MA, CT and RI, depending on primary dates. If things broke his way and he was the only moderate-ish candidate left by Super Tuesday, he could eek out wins in states like Illinois or New York, too.
