Bava Kama Chart #11

1. The Rashba writes that it is preferable to the master to receive the Peros from all of the payments (Nezek and Sheves) over receiving only the Guf of the Sheves. Therefore, the Chachamim instituted that the master receive what is preferable to him.
2. The Ramah and Rabeinu Yehonasan (in the Shitah Mekubetzes) write that the master is not entitled to receive the money of the Sheves, since he has already received the money of the Nezek which compensates for the loss of work of the Eved. The payment of Sheves is only for the loss of *secondary* work that the Eved could have done while he was performing his primary work (see Insights to 85b, in the name of the Ba'al ha'Me'or). A master, though, cannot force his Eved Ivri to do two forms of work at the same time, and therefore the master does not receive the payment of Sheves. However, he receives the Peros of the Sheves; since he did not receive the payment of the Nezek in its entirety, but only the Peros, the Chachamim gave him the Peros of the Sheves as a supplement.
The reason they gave him only the Peros of the Nezek and not all of it, writes the Ramah, is because the payment of the Nezek includes the value of the Eved's hand (or whatever body part was damaged), and not just the value of the lost work, and the hand is solely the possession of the Eved. The master has no share in the hand itself, he only has a Shi'abud to the work that the hand performs. The payment of the Nezek must therefore go to the Eved, so that he will remain with some of that money when he goes free. The Peros alone go to the master, to compensate for the Eved's labor that he lost.
Rabeinu Yehonasan explains that the reason the master does not receive all of the Nezek payment is because we rule (Kidushin 16a) that if the Eved Ivri becomes sick and can only perform a very light labor (for all six years of his servitude), the master loses out. For this reason, when the Eved Ivri was damaged and could only do light work there is no need to compensate the master even with the Peros of the Nezek payment. Nevertheless, we do give the master at least the Peros of the Nezek. The reason for this is because the Nezek payment itself is not deserved, but rather "the Torah had mercy" on the Nizak (the Eved) and granted him Nezek payments. Since the entitlement of the Eved to this payment is only due to the mercy of the Torah, we, too, have mercy on the master and give him a portion of this payment to make up for what he lost by the damage done to his Eved Ivri. (This is similar to the explanation of the Ramah.)
3. The Pnei Yehoshua explains that the Gemara is referring to a case where the Eved became sick (such that he was unable to work at all) for under three years. Since the Eved was prevented from doing work for *less* than three years, we rule (Kidushin 16a) that it is the master's loss even if the Eved could not do *any* work during that time -- not even light labor. For this reason the master does not receive the Sheves payments. Nevertheless, we give the master the Peros of the Sheves payment, since Hashem had mercy on the Eved and let him receive the payment of Nezek, as described above, end of (2):2. (Rabeinu Yehonasan, too, alludes to this explanation.)
4. See Nesivos ha'Mishpat (363:2), who points out that since the Eved is considered the property of the master, and he is not a limb of the master himself, it would seem that the master should not receive payment for his Eved's Sheves at all, just like he does not receive any payment of Sheves (but only Nezek) when his animal is damaged. Perhaps it is because of this reason that the master does not receive the actual payment of Sheves for his Eved. (Nevertheless, since he does not receive the entire payment of Nezek for his Eved, but only the Peros, the Chachamim supplemented his loss by giving him the Peros of the Sheves, as mentioned above in answer (2):2.)