I recently encountered this sentence in a news story:
Traditionally, state parties perform the basic blocking and tackling of politics, from get out the vote programs to building data in municipal elections.
I assumed that the phrase blocking and tackling was a slightly odd variation on block and tackle, a system of pulleys and ropes.
But then I realized that blocking and tackling are both things that are done in American football, and I thought maybe the phrase was sort of like an eggcorn—someone hearing block and tackle used metaphorically, and assuming it had to do with football, and thus treating the words as verbs instead of nouns, and thus ennounifying them by adding -ing to each.
Which was a fun theory as long as it lasted, but then I did a web search for blocking and tackling and discovered that I was the one who was making mistaken assumptions about phrase origins.
Because American football coach Vince Lombardi apparently once said, “Football is two things. It's blocking and tackling.”
And so apparently the phrase blocking and tackling has come to be used, especially in business and politics, to refer to the basic unglamorous work that underpins the higher-profile work.
I suppose this is more or less a phrase homomorph—the two phrases look (almost) the same, but come from different roots.