We’re at the half-way point of the 2013 campaign and one of this season’s best kept secrets is the fine crop of rookie hurlers this year.

Don’t know about Jose Fernandez or Julio Teheran? Here’s your opportunity to find out.

Here are rookies currently qualified for the ERA title. Note especially the ages of the pitchers at the top of the list.

Three of the top four by ERA+ are 22 or younger. How often have pitchers that young had 90 IP and an ERA under 3.00 half-way through their rookie season? Very seldom.

That’s the complete list from P-I Split Finder, back to 1916. Note that the ERA+ scores shown above are for the entire rookie season, not just the first half.

Pretty good company with a couple of HOFers, several other notables, and a few what-might-have-been names. The two pitchers on this list this year doubles the total for the preceding 28 years. It’s first season with a pair since 1978 and only the fourth such season overall.

With his 3.12 ERA, Julio Teheran barely missed the list above. But, he joins Miller and Fernandez  to make three rookies 22 or younger with an ERA+ of 125 or better. Were the trio to hold that form for the season, it would be the most rookies aged 22 or younger in the same year.

What are the chances? I would probably say slim, except that, instead of starting fast and then coming down to earth the second and third time through the league, it’s been the opposite for Fernandez and Teheran. Consider:

• Fernandez has trimmed his ERA from 4.50 for April, to 3.78 at the end of May, and 2.72 now. The Marlins are 9-7 when Fernandez starts, and 21-45 when he doesn’t.
• Similar story for Teheran, going from 5.08 for April, to 3.71 at the end of May and 3.12 now. Teheran has also turned up the heat on opposing batters with 46 strikeouts over his last 39 innings, after a more modest (by today’s standards) 35 strikeouts in 56.1 IP to start the year.
• Miller has been solid right out of the gate, allowing no more than 3 runs in any of his first 12 starts and keeping his ERA under 2.00 through most of that stretch. He’s run into a little rough patch of late with a 6.38 ERA over his last 4 starts, including his first disaster in his most recent outing, allowing 5 runs over just 1.2 IP. His 101 SO to just 22 BB is easily the best ratio of the three.

The “grizzled veteran” of the four pitchers topping our first list is 26 year-old Hyun-jin Ryu of the Dodgers. I’ve seen Ryu pitch a few times and his maturity is evident. Never seems to get flustered and just goes about his business, working quickly but not hurriedly. Doesn’t have the blazing heater, but is very precise with his location. Ryu has gone 5+ innings every time out with 14 quality starts in 16 outings, including a shutout of the rival Angels. Has also helped himself with the lumber, with 3 extra-base hits and 3 RBI to his credit.

What young pitchers have caught your eye this season?