Is DNC shenanigans an unlikely explanation? Who is this Buttigieg guy and why did he suddenly beat Sanders in Iowa? I read a bit about some donations to the Shadow App company, and the fact that the company didn't exist for very long prior to being used to manage the vote(!). I read somewhere about a connection to the Clintons who totally didn't conspire to undermine Sanders at any point in recent history... I can't really be arsed, but I wouldn't use Hanlon's razor in this age of barely veiled political corruption.
In talking to folks who canvased in Iowa, they ran into an awful lot of Buttigieg supporters. On top of that, both Biden and Klobuchar were not viable in an awful lot of precincts (not from Iowa democratic party reports, from people who were not supporters of any of those three candidates who were live tweeting their experience caucusing). In a precinct where both Klobuchar and Biden were not viable but Sanders, Warren and Buttigieg were, which of those three candidates do you suppose all those Klobuchar and Biden supporters realigned to?
And even if none of that were the case, the problem with falsifying caucus results is that people where there, they remember how many people supported their candidate and what the viability threshold was, and they can and do look up the reported numbers for their specific precinct. Heck the Sanders campaign was able to independently gather and record the results from about 40% of precincts the same night as the Iowa caucuses took place, which is a damned sight better than the Iowa democratic party managed.
Love them or hate them (and most people seem to hate them) it's an awful lot easier to catch any attempt to
systematically falsify* the results of a public caucus where everyone sees who everyone else in their precinct is voting for than to catch people who are systematically falsifying the results of an election based on secret ballots.
*You can do all sorts of other unethical things to influence the results of a caucus that would be harder in an election based on secret ballots. Breaking the rules or selectively enforcing them. Doing delegate math wrong. Peer pressure to vote a certain way since your neighbors can see and judge you. But if people vote one way and you decide to report something else, you're going to get caught.