It depends on how well they play... I'd take another Bak in the first round.
That being said, I don't think I'd take an interior OL in the first unless I thought they were a potential future NFL hall of famer! Like Jack Conklin SOOO reminded me of Steve Hutchinson... though also depends on scheme, the more power running we plan on doing, the more I might be willing to use a high pick on an interor OL.
Yeah, a top 15 pick for a G may be a reach. Most G's don't go in the first round and if they do, it's towards the end of the round generally. In 2017 the first G off the board was at 38, and the next two went 63 & 64. The top OT went at 20. In 2016 there were 4 OTs in the top 16, but the first G went at 28. In 2015, the top G was 28 as well. So that's an average position of 31 for the top rated G over the last 3 years.
Edit: Whoops, I left out 2018. The colts picked a G at 6 in 2018. So that's an average position of 24 for the top rated G in the last 3 years.
Going back further, in 2014 the Cowboys took Zack Martin at 16, and he seems to be pretty good. In 2013 there were 9 OL in the top 20, 5 OTs and 3 Gs, so that was a pretty exceptional year for OLs. In 2012 we're back to normality with Gs at 24, 28, 40 and 44. 2011, 23 and the next off the board is at 55. 2010 we have another mid round G at 17, but no other Gs until the 3rd round.
If there is a top 3 OT at 15, that would make sense. A G with the Saint's 1st round pick would make sense if they are the top rated at the position. A top 3 G with the 2nd round pick would make some sense too.
So yeah, a G at ~15 or so? If it's a transcendent sort of player at the position sure. I don't know enough about any of the players coming out to really say. Reaching a bit might make sense if it's a very good player and it isn't generally a good year for OL, for instance if there is a big drop off after that first guy.
Here's a random sample of interior OLs from mock drafts:
18 ,26, 42 Cody Ford (G)
21, 45, 48, 67 Chris Lindstrom (G)
32, 38, 48 Tyler Biabasz (G/C)
46, 49 Elgton Jenkins (C)
50, 51, 78 Erik McCoy (C)
54, 69 Beau Brezschawel (G)
58, 96 Connor McGovern (C)
It looks like most of these guys are projected as 2nd round prospects or so. But again, I don't know enough to have opinions on any specific player.