Lol. Great gotcha! They were 28th (3rd receiving votes), had been ranked the week before, and were about to be ranked the next day. They had just made their conference title game beating the top seed #18 along the way. The point is not actually the ranking, the point is how people felt about the team at the time. People thought they were top 25 good (many of their metrics were top 20 on top of being ranked a lot this season), so sweeping them (and winning there on the road) was seen as very good for Boise St.
The metrics do not all "clearly favor the MWC." 1 of the 2 predictive metrics on the committee's teamsheet, BPI, is mechanically biased against the MWC (there is a controversial elevation adjustment which hits many of the MWC home wins hard). SOR, 1 of the 2 resume metrics on the teamsheet, uses BPI as the base of it's calculations (like WAB uses T-Rank). This is one of the biggest reasons why the MWC was almost universally seeded lower than the consensus/BracketMatrix. I'm not sure what you mean the conference has never had good showings in the tournament. San Diego St literally made the title game last season.
San Diego St. is 70-6 at home the last 5 years. 92% winning %. They won 14/15 at home this year. They're 24-3 at home the last 3 years in conference play (88%). Generously counting the semi-neutral Gonzaga and St. John's in the BET wins, UConn went 9-3 on the road this year (75% and much worse last year). Winning on the road is really hard. Yeah it's probably pretty comparable to beat this year's UConn team at your place vs. SDSU at their place.