The Oxford American Prayer Book Commentary from 1950 by Massey Shepherd, suggests there is little rationale for the specific ordering of the Epistles and Gospels.
The early Roman system of reckoning the Sundays of this season was to group them about certain fixed feasts. … Medieval sacramentaries and missals developed other schemes of numeration, some dating the Sundays after Pentecost, and others after Trinity. The result was a dislocation of many of the propers originally belonging together. The Prayer Book of 1549 made further alterations, so that there is seldom a unity of theme in the propers for these Sundays. In most cases we have no way of knowing the reason for the selections in the first place, except that the Epistles preserve relics of a course reading.
So if we take this as the sum of scholarship, we will not even look for a detailed rationale. And in fact the skewing of the Epistles from the related Gospels in the Roman missal, as pointed out by David Curry, does in fact mean that Epistles and Gospels in this season do not form as coherent a teaching on any given Sunday in the Roman missal. The scholarship which Shepherd sums up was used by the Roman Catholic Church and mistakenly taken by our own Church as part of the justification for replacing the Traditional one year lectionary that we have in our Book of Common Prayer with the modern three year Eucharistic lectionary.
But the modern understanding that a rationale is unknowable because of all the dislocations of the propers only applies to the lectionary preserved in the Roman missal. The situation for Anglicans is different. Our lectionary can be compared with The Comes of St. Jerome, a 5th century lectionary attributed to St. Jerome but which some scholars believe was developed by Claudianus Mamertus. Robert Crouse did the comparison and found that the Comes of St. Jerome has largely the same lections as are found in the Sarum missal – the medieval lectionary used in Salisbury Cathedral and which has largely been kept intact in our Book of Common Prayer. Sunday by Sunday throughout Trinity season the readings are very close.