Neither of these guys were supposed to pitch like this. Don't get me wrong, they're both solid pitchers, but they weren't supposed to do this. And yet here they are, sitting second and fourth in the NL in ERA, respectively. While they're both pitching like this, there's no say this wasn't going to be number one.
2. Jonathan Gray (0-1, 7.98) vs Johnny Cueto (4-1, 3.61)
This one has a lot of intrigue to me personally, so it's quite possible I'm giving it too much credit.
I did an exhaustive breakdown of Gray just the other day, which can be found here. I might have made a mistake of sorts, using all my bullets on that piece and not saving any for this post. Oh well. If you're wondering why I think a matchup featuring a guy with a 7.98 ERA can be the second best of the day, read that piece. If you don't want to do that, suffice to say Gray has pitched much better than his ERA would indicate.
3. Ervin Santana (0-1, 3.15) vs Chris Sale (6-0, 1.66)
What a month for Chris Sale! He missed having a six win month by just one day (his 6th start was on May 1st), posted a 1.66 ERA, and won the official Pitching Breakdowns April Cy Young Award , which I'm sure will take a prominent place on his awards shelf. Or maybe at least his fridge or something.
I briefly noted his lack of strikeouts so far, and I noticed as I was researching for this article that August Fagerstrom did a nice piece on Sale's apparent new approach on Wednesday, which I recommend you read.
Although he clearly plays second fiddle to Sale in this matchup, Santana has actually pitched quite well this year. His ERA has obviously been great, and it's fully supported by his 3.13 FIP, though both numbers are kept low by his 4.8% HR/FB ratio. An interesting note about Santana is that he's getting a ton of pop-ups, with his 6.7% PU/BIP ratio more than doubling the league average (3.2%). That partially explains the low HR/FB ratio.