Booker says that in this stage "the hero is in some way incomplete and unfulfilled and his thoughts turn towards the future." Mr. Guizac and his family have arrived in the United States with only the most basic of possessions. Assuming he does not enjoy being homeless, Mr. Guizac probably does feel "incomplete." We don't hear his thoughts but we can assume from his actions that he sees the farm as an opportunity to do good work, and get ahead in this new world, a world that is supposed to be kindler and gentler than the one he and his family fled.
In this stage "things seem to be going improbably well for the hero." We wouldn't go as far as "improbably well" in the case of Mr. Guizac, but things are going OK. Everyone is fed, clothed, and housed; money is apparently being saved; the salary has been raised to cover the additional duties he took over from Mr. Shortley; and he has a workable relationship with Mrs. McIntyre. You can tell because she keeps buying him new machinery, which means she's making money, which means she's happy. This all means that although Mrs. McIntyre is exploiting Mr. Guizac, she isn't making his job any harder than it has to be.
During this stage "almost imperceptibly, things start to go wrong" and "a 'shadow figure' may appear, seeming in some obscure way to threaten him." When Mrs. McIntyre confronts Mr. Guizac about the fact that he's arranging a marriage between his cousin and Sulk, he probably underestimated the nature of his offense. In Georgia (perhaps the implied setting of the story), as well as most of the American South, interracial marriage was illegal until 1967. This is only part of the problem. Mrs. McIntyre has her own reasons for disapproving of the situation.
When Mr. Shortley returns to the farm having buried his wife, the pressure is on for Mr. Guizac. Mrs. McIntyre is openly repulsed by Mr. Guizac and keeps him around in part for the money, but also because she's afraid to fire him. Mr. Shortley is complaining all over town that Mrs. McIntyre is giving preference to "foreigners," over American veterans like himself. The town responds by pressuring Mrs. McIntyre to fire Mr. Guizac. Again, we never read Mr. Guizac's thoughts, but we can assume that he can sense the hate directed at him. This situation qualifies as a nightmare for our hero.
In this stage, the hero is killed or destroyed, often as a result of his own "recklessness." Mr. Guizac is certainly destroyed at the end, killed by the very machinery that was supposed to help him make a new life for himself and his family. We're not sure that Mr. Guizac behaved in reckless manner. In the end what kills Mr. Guizac is silence, the silence of Mrs. McIntyre, Mr. Shortley, and Sulk when they fail to warn Mr. Guizac about the tractor rolling toward him.