sometimes I just like to think about Elias sitting in his office and making his little Archivist plans. obviously choosing Jon is a no-brainer because Jon already has a Web mark and that's the hardest one to manipulate into happening
and Jon asks for Tim and Sasha, which okay, fine, Tim's an explosion waiting to happen and Sasha's good cannon fodder if nothing else. but Jon likes and respects them both so they're not really going to create the atmosphere of anxiety and fury that Elias very much wants his new Archivist to be suffering from the get go. so whomst to choose?
Martin has got used to life in the library and just isn't pumping out that good good CV related terror any more because he's pretty confident now that he can actually do the job. but put him down in a whole new position and he's going to be right back where he started! terrified of being caught and going ridiculously above and beyond to try to make a good impression. and that exact anxiety and going above and beyond is going to INFURIATE Jon. plus Jon only has a bachelor's degree and Martin's CV says he has a Master's, and in a field that's actually relevant, which means that Jon's going to feel like he's starting from an incredibly inferior position relative to Martin and is going to be wildly anxious and angry about that. and when Martin reveals himself to be totally incompentent... even worse! (even better from Elias's point of view)
I like to think about Elias having a huge spreadsheet of everyone in the Institute in which he scores them on how badly they'll infuriate and terrify Jon, and Martin comes out the clear winner.
and like at first it really seems to be working! Jon hates Martin! except... after the worms, why does he keep on going out to lunch with Martin despite believing him to be murderously plotting his downfall?? why would finding out that Martin lied on his CV make Jon trust Martin MORE instead of less??? WHY THE HELL IS HE FALLING IN LOVE WITH MARTIN????? this wasn't supposed to happen! Elias made a spreadsheet and everything!!!
also I think Elias totally has the hots for Martin because he reminds him of Peter and this just makes him hate Martin even more, but that's by the by