From what I've observed:
1. Chris Ballard is an outstanding GM. His draft and free agency philosophy is a winning one; it did help to have prime position, but he maximized value. I do believe he is improving the roster, but it takes the right coaching, scheme, player chemistry, and QB play for success. Also their owner is a crackhead, moron, idiot, meth head, dolt, and yes, that does make a difference.
2. Frank Reich is not a special coach in any way, or at least there is absolutely no evidence to support that statement. There's nothing specific you can cite other than a record turnaround, which happens all the time in the NFL and often proves to be caused by other factors (schedule, a roster better than thought, return of your franchise QB as in this case.)
3. The author is clearly a huge homer. It reads more like a fan post by someone with no objectivity just assuming everything works out 110% right.
4. I noted last year that the Colts did not actually improve during the season. Their schedule was just backloaded with crap opponents. They still struggled badly against quality opponents outside the division, which has been the hallmark of the Luck era Colts. That's why I went against the grain and picked the Chiefs to beat them easily while many thought the Colts had ascended to a new level.
5. Turnarounds that happen with last-place schedule don't mean that much. It was an overall really crappy schedule. They played the (2017) last place Raiders and Bengals, avoiding division powerhouses in the AFC West and AFC North. They played the horrendous NFC East. This year they play the AFC West and NFC South, along with the second place Steelers and Dolphins.
6. I'm not saying the Colts aren't going to be good. But the title and presumptions made are incredibly arrogant if not flat out stupid. They proved they can go 10-6 with a last place schedule, still struggle badly against quality opponents, and get whipped against elite teams. They have a lot of ground to cover. The Steelers (I believe they'll be better without those two idiots), Chiefs, Chargers, and Texans all have just as legit of an argument to be able to challenge NE.