I’m not sure biblical translators “get it right” oftentimes, in translating the NT scriptures; e.g., the following in Greek: πάντες ὅσοι πρὸ ἐμοῦ ἦλθον κλέπται εἰσὶν καὶ λῃσταί ἀλλ’ οὐκ ἤκουσαν αὐτῶν τὰ πρόβατα [John 10:8]
the way the passage is translated by them, limits the scripture to only “past tense,” of eithion or “COME” not inclusive of present tense of “CAME.” what do you think? 
οὐκ ἔρχονται νῦν οὖτοι οἱ κλέπται καὶ οἱ λῃσταὶ, ἀλλά ἦλθον πρὸ Ἰησοῦ.
σύμφημι ἔγωγε. καλαὶ οὖν καὶ ἀκριβεῖς εἰσι αἱ μεταφράσεις.
To paraphrase our Greek-writing friends, what you’ve just written has loads of mistakes in it. It is certainly talking about the past (the form ἦλθον is aorist indicative and refers to the past), and the words πρὸ ἐμοῦ (“before me”) also refer to the past. I don’t know how you would understand it otherwise.
If I were in your shoes, I wouldn’t criticize the hard labor that translators put into their works. If you don’t know that ἦλθον is past, that it is ēlthon and not eithion, that the present tense of the verb in the NT would be ἔρχονται, etc., who are you to judge their work, which in this case is spot-on?
I’m not one to criticize either scripture or the translation thereof, but I found it rather baffling for both ἦλθον and εἰσὶν to be finite and without conjunction, but perhaps I’m just not at the level to read the New Testament. I’d appreciate someone’s shedding light on this.
Having looked at the official translation (KJ “All that ever came before me are thieves and robbers: but the sheep did not hear them”), I’d expect that at least one would be a participle, or for the phrase denoting the coming to be governed by a relative pronoun, as in English.
If this appeared in a translation assignment from English to Greek, my professor would definitely expect a participle use, such as something like πάντες ἐλθόντες πρὸ ἐμοῦ κλέπται καὶ λῃσταί εἰσιν, ἀλλ᾽ οἱ ὀΐες (this is slightly more literal than I would like, but it’s the only word for ‘sheep’ I know) οὐ τούτων ἤκουσαν.
The term to look up would be “substantival clause.” It’s like in the Anabasis when Cyrus tries to knock some sense into Clearchus and Menon and says: “οὐκ ἴστε ὅ τι ποιεῖτε.”
In John 10:8 you can think of “πάντες ὅσοι ἦλθον πρὸ ἐμοῦ” as one great big noun. Once you do that, it should seem like a simple sentence.
That said, at some point in the textual tradition πρὸ ἐμοῦ was either inserted or dropped out. I can see it as an insertion. After all, a copyist might want to clarify “πάντες ὅσοι ἦλθον κλέπται εἰσὶν καὶ λῃσταί.” I can also imagine John writing it correctly in the first place and the two words dropping out in a copied text.
I would have to get out my NA magic decoder ring to say anything about the manuscript tradition of that verse, and that would just be pointless since there are others more knowledgable than me about that.
Forgive me. I completely omitted ὄσος when I read the original, resulting in a defective understanding of the sentence. Your explanation only served to clarify it further. 
οἱ ἐμοὶ προάγγελοι?
οὐκ ἐστὶν ὁ Ἰωάννης ὁ προάγγελος τοῦ Ἱησοῦ; τοῦτο ἐμοί δοκεῖ.
ὁ Μάρκος ὁ εὐαγγέλιος ἔλεξεν ὅτι: Ἰδοὺ ἀποστέλλω τὸν ἄγγελόν μου πρὸ προσώπου σου…ἐγένετο Ἰωάννης ὁ βαπτίζων ἐν τῇ ἐρήμῳ. Διὸ ὁ Ἰωάννης ἐστί προαγγέλος. Ἀλλὰ ὅς οὐκ έστιν κλέπτης ἤ λῃστής. δοκεῖ ἐμοίγε ἴσων πάντες ὅσοι ἦλθον πρὸ Ἰησοῦ ψευδόχριστοι εἰσὶν καὶ ψευδοπροφῆται.
εἰ γὰρ ῥᾴονα καὶ ἐν English γεγραφότες εἶτε ὥστε μοι ταῦτα γνῶναι. 
While I don’t think there’s an English policy around these parts, I would really love to understand what’s being discussed at such length in Greek.
do you mean something like: … αἰτίους γενέσθαι τῆς τοῦ
λεγομένου κατὰ Μᾶρκον εὐαγγελίου γραφῆς.
or
Ταῦτα μὲν ἐν τῷ κατὰ Μᾶρκον εὐαγγελίῳ γέγραπται·
τοῦ κατὰ Ματθαῖον εὐαγγελίου
τοῦ καθ’ Ἑβραίους εὐαγγελίου
Try finding ὁ Μάρκος ὁ εὐαγγέλιος in a greek text. That will provide a clue to its status as an idiom.
Thanks C.S.! But the reason you won’t find it in a Greek text is because I mistakenly called Mark by the Attic epithet rather than the Koine (making him a giver of good tidings rather than a bringer of them), which would not be quite correct. I should probably have said ὁ Μάρκος ὁ εὐαγγελιστής, which I think is perfectly good Greek. See Acts 21:8 for an example.
But please, continue to critique anything that you find wrong with my Greek. I appreciate all the comments!