And please, answers like "they are all imports from Russia" (which was once provided to me on another forum discussion) won't make the cut because as is well known it is Ukraine that tends to provide priests for the Russian Orthodox Church and not vice versa.
It may just be me, but I must in honesty write that I tend to be suspicious of questions put in this format. I will, however, assume that this is an honest query, and attempt to provide my own speculation, although I do not believe it is, as you state, "a simple question".
I believe the biggest factor is that the UOC-MP remains in control of more parishes, even if they would rather be part of another church. Many priests, especially those coming from the ROC days, are reluctant to give up their homes, jobs, and pensions. Please remember that the UOC-MP in most places inherited the property of the ROC. Therefore, unless a parish takes actice steps to re-register from the UOC-MP to another church, it will remain listed as a UOC-MP church. All the priests serving those parishes are counted as priests of the Moscow Patriarchate.
Even when a parish does try to re-register, there are obstacles because allocation of church buildings in Ukraine is decided in the first instance by local authorities, and is therefore subject to influence outside of the local congregations. Most famously, for example, in a case decided on June 14, 2007 and cited in the U.S. State Department's International Religious Freedom Report (2007), the European Court of Human Rights ruled that the Kyiv city administration was violating the rights of the faithful of the Svyato-Mykhaylivska parish in Kyiv by not allowing them to reregister from the UOC-MP to the UOC-KP. That is, the faithful of that parish overwhelmingly wish to be a part of the UOC-KP, but the civil authorities force their church (and its priest) to remain in the UOC-MP.
That is just one documented case. In fact, even though a survey in December of 2006 showed that 52% of the adults in Kyiv suported the Kyivan Patriarchate, compared to only 8% for the Moscow Patriarchate, the Kyiv City Council that same year granted the Moscow Patriarchate title to 10 churches and only 1 to the Kyivan Patriarchate (and one to the UAOC, whose followers represent less than 1% of the population of Kyiv).
Additionally, the UOC-MP is able to draw on graduates from not just the seminaries in Ukraine, but also to send students to study in Russia, and has more money to send more students to school. Until recently, there was a realistic hope that the UOC-MP would receive autocephaly within a realistic future, so it would not be hard to imagine that there were future priests who were willing to take that route.
It would also not be incorrect to note that there has in the past 12-15 years indeed been a visible influx of burly Russian-speaking monastics taking up residence in the UOC-MP's monasteries in Ukraine, most famously and visibly in Rivne. All of these count as clergy, as well.
While I do make an honest effort to answer your question, I am more comfortable simply reporting on what is, as I do in the post above which you question, rather than to try to answer why things are, as you ask me to do.
Yours in Christ,
Priest Paul Koroluk, UOC-KP
