Kommentar zu Bereschit 31:8

IF HE SAID THUS: THE SPECKLED SHALL BE THY WAGES. The meaning thereof is that at first Laban agreed to give Jacob the two appearances the speckled and the spotted — also the brownish lambs. Then he retracted and agreed to give him another color, and thus he changed it every year. The flocks, however, gave birth accordingly. This was not due to the power of the sticks, for he was telling them of the deed of the Great G-d who treated him wondrously each and every year, just as he said, But G-d suffered him not to do me evil.¹⁷⁸Above, Verse 7.
It is also possible that Laban changed his wages after the flocks became pregnant and gave birth in accordance with Jacob’s will, it pleasing the Creator to do so. [In this case, it clearly was not due to the power of the sticks.] And so we find in Bereshith Rabbah:¹⁷⁹74:2. “The Holy One, blessed be He, foresaw what Laban was destined to do to our father Jacob, and He created the form of the sheep to conform to the colors Laban was to stipulate. Thus, it is not written here, ‘If he said (amar) thus,’ but it is written, ‘If he will say (yomar) thus,’” [indicating that G-d foresaw what Laban was destined to stipulate to Jacob].

וילדו כל הצאן, this percentage could certainly not all be attributed to exposing the sheep to the peeled sticks.

אם כה יאמר, "If he said thus, etc." Although the original condition had been that Jacob should take the spotted and speckled ones, he did not honour his word but agreed to give him only one of these two.

אם כה... כל הצאן, the word כל need not be understood literally as “all.” It means simply: “most.” We have many examples in Scripture when the word כל does not mean “all,” but “most.” A well known example is Genesis 41,55 וכל הארץ באו מצרימה, which cannot mean that everybody came to Egypt, but must mean that most people from the neighbouring countries sent representatives to Egypt to buy food there during the famine in their own land. Although in our verse onlyנקודים and עקודים are mentioned specifically, the same applies to טלאים.

אם כה יאמר: נקודים יהיה שכרך, וגו', “if he would say thus: “the blotched ones will be your wages, etc.” Originally, Yaakov had stipulated two skin patterns among the goats, as well as the colour brown when it would show up among the sheep. When the result favoured Yaakov, Lavan changed the terms of the agreement, substituting skin patterns which had been rare up to that point. However, as soon as he did so, the animals bore young with the skin patterns which favoured Yaakov disproportionately. The new skin patterns were already totally unrelated to anything Yaakov could do by peeling them and patterning them. It was clear that without Divine intervention on behalf of Yaakov, he could not have become so rich in so short a period of time. We know this from the fact that Yaakov did not add that he had to use these stratagems again and again.

Another reason is that originally the ankle-striped ones had not been included in the agreement at all. Laban therefore argued that those certainly were not part of Jacob's share. The fact that Laban did not admit the truth can be seen from the fact that he had removed this category of animal, whereas later on he negotiated with him about exchanging them for animals with a different skin pattern. This kind of wheeling and dealing was repeated no fewer than ten times. All the while the original conditions remained legally valid.

The reason the Torah describes this as in the future, i.e. ואם כה יאמר, instead of אם כה אמר, may be support for my theory that Laban hastened to change the terms of the agreement as soon as the animals were in heat and conceived, but before they actually gave birth again. Clearly Jacob's success was not due to his own machinations but only to G'd's intervention on his behalf.