You're bringing up a bunch of anecdotal evidence and evidence based on feels. Rallies, enthusiasm, and energy are not how you measure campaign performance. You do it with statistics.
Imagine where we'd be if Sanders had run a better campaign. We know the opportunity is there to beat Hillary. We saw it in 2008. The Obama campaign did it by targeting young and non-white voters and turning them out. Sanders got the young voters (although not enough), but completely missed out on nonwhite voters. Making gains in nonwhite voters is the big difference Hillary made from 2008 to 2016, which gave her the victory.
The Democratic Party has large amounts of nonwhite voters. A lot of states have 45-55% nonwhite voters. And in most states, Sanders only won 25-35% of them, which just doesn't cut it in the Democratic primary. Merely tying Clinton in the nonwhite vote would have turned a 10 point loss in to a 2 point loss, a 2 point loss into a win, and a 2 point win into a 10 point win. And because delegates are awarded proportionally, that makes a huge difference.
Let's look at Florida. Clinton won 64% of the total vote and 141 pledged delegates to Sanders' 73. And she won 75% of the nonwhite vote. If Sanders merely split the nonwhite vote with Clinton, she would have only won 51% of the total vote and pledged delegates and Sanders would have had an additional 30 delegates. Sanders was 180 delegates short of the magic number. The additional delegates gained from simply tying Clinton in the nonwhite vote in one large state would have cut Sanders' deficit by 16%.
Sanders performed the same in other large states. The nonwhite vote is 41% in New York. Sanders got 32% of that. Tying the nonwhite vote in New York would have brought Clinton's share from 57% down to 51%. Sanders would have gained 13 more delegates. Along with Florida, those 43 delegates would have cut his deficit by 24%.
Let's move to Texas. The nonwhite vote is a staggering 57%. And Sanders again won 25% of that. Tying Clinton in nonwhite voters would have brought her margin from 65% down to 52%. Sanders would have added 30 more delegates. Add that to the 43 from Florida and New York. Now, we're at 73 delegates, a 40% reduction in the delegate deficit, just from tying Clinton in the nonwhite vote in three large states.
How about some states Sanders very narrowly lost? Massachusetts only had 15% nonwhite turnout and Sanders won 41% of that. But even there, tying the nonwhite vote would have made a difference. It would have won Sanders the state. Only a difference of one delegate, but still, it would have been nice, wouldn't it? Tying the nonwhite vote would have won him Illinois as well and gotten him nine extra delegates.
People have been scapegoating the media since the beginning of politics because it's easier to blame them or a party or some vague notion of fraud than it is to simply acknowledge and accept defeat. You don't have to look to the media or the party when Sanders' shortcomings are so clear. He couldn't get his message out to enough voters and turn enough of them out. I would attribute this to his campaign manager, Jeff Weaver, who had never run a campaign outside of Vermont before. Compare that with David Plouffe, a veteran of campaigns at all levels of government in many states, and it's no wonder Sanders lost.