Does transubstantiation explain the eucharistic transformation? At first glance it may certainly seem to, and no doubt many Latin theologians in the past have thought that it does. Certainly the many Eastern theologians in the past (and we are talking some 500 years here) who have explicitly employed the term "transubstantiation" and the notion of substantial change did not understood it as an explanation or definition of the real presence. They employed it because they found it a useful way of speaking, especially as a way to distinguish Orthodox understanding of the Eucharist from various heterodox teachings.
Is transubstantiation alien to Orthodoxy? Yes, if it is understood as a philosophical explanation of the eucharistic change; but once that qualification is made, it clearly is not alien. Orthodox bishops, priests, theologians employed the notion of substantial change for centuries. They unabashedly used the term "transubstantiation." I have already mentioned the 1672 Synod of Jerusalem, which until fairly recently was highly regarded throughout the Orthodox world. The 1727 Council of Constantinople went so far as to declare: "As an explanatory and most accurately significant declaration of this change of the bread and the wine into the body of the Lord itself and His blood the faithful ought to acknowledge and receive the word transubstantiation, which the Catholic Church as a whole has used and receives as the most fitting statement of this mystery." In 1838 the decrees of the Council of Jerusalem were received by the Holy Synod of the Russian Church, with some minor modifications: specifically, the statement "the substance of the bread and wine no longer remain" was altered to "the very bread and wine no longer remain" and the phrase "under the accidents of the bread" was omitted. And as already mentioned in this thread, the term transubstantiation was incorporated into the catechetical teaching of the Russian Church in St Philaret's Longer Catechism, which eventually received the approval of all the Eastern patriarchs. In 1725 those elected to the office of bishop were required to affirm:
I do believe and understand that the Transubstantiation of the body and blood of Christ in the Lord's Supper is made, as the Eastern and ancient Russian doctors teach, by the influence and operation of the Holy Ghost at the invocation, when the bishop or priest prays to God the Father in these words, "Make therefore this bread the most honorable body of Thy Christ."
Whether this declaration is still a part of the ordination office I do not know, but it apparently was still a part of the office at the turn of the 20th century. (For a survey of Eastern reflection and teaching on the Eucharist from the 6th through the 19th century, see Darwell Stone, A History of the Doctrine of the Holy Eucharist, chap. 4.)
Even as late as 1961 Panagiotes Trembelas could write in his Dogmatics of the Eastern Church: "We are in accord in this with the Roman Catholics in believing that in this marvelous transformation, although the exterior phenomena and the accidents of bread and wine remain, all their substance however is changed into the Body and Blood of the Lord." Eleven years later Archbishop Methodios Fouyas, in his book Orthodoxy, Roman Catholicism and Anglicanism, confirmed this judgment: "Roman and Orthodox teach that by the words spoken in the Holy Eucharist the species of bread and wine are changed into the Body and Blood of Christ, so that although these species have the outward qualities of bread and wine, essentially they are the Body and Blood of Christ."
Contemporary Orthodox theologians apparently now believe that substantial change is not the best way to speak of the eucharistic transformation (though given that my acquaintance with Orthodox theology is restricted to works written or translated into English, I do not know that this is in fact the case). I happen to agree but not for the reasons offered by Owen. I hope to elaborate on my present opinions in a future posting, but let me say this at the moment: transubstantiation, especially when packaged with the liturgical practices of unleavened bread and infrequent communion (the latter no longer obtaining today), makes it more difficult to speak of the Divine Liturgy as eschatological banquet. I think this is the heart of Meyendorff's concern. Or to put it somewhat differently, the Incarnation is the descent of God to the world; the Eucharist is the ascent of the world into heaven. Because transubstantiation is so easily misunderstood as signifying the material change of the bread and wine, it becomes more difficult to speak of the eschatological nature both of the Divine Liturgy as a whole and specifically of the eucharistic change. But more on this later.