Why he's getting picked up in Fantasy:
Eight starts into the season and he's given up less than three runs in six of them. It also helps that he's racking up decent strikeout totals and a 2.09 ERA never hurts either.
What to expect going forward:
Coming into this year, Arrieta had the appearance of just another back-end starting pitcher. I was able to jump on top of things and pick him up last night (thus benefiting from a very strong performance yesterday, 1 win, 11 K's...oh yeah).
There is some evidence that he has turned the corner as he is inducing more ground balls and even his FIP & xFIP are both below 3. Even better, there is some evidence that this improvement is not a pure byproduct of good luck as his BABIP is .325 indicating his numbers could have even been better coming into today with better luck.
An ERA around 2 and 11 K's per start is probably too much to expect going forward but his luck in HR/FB% may catch up to him sooner rather than later. I think he'll be a good source of strikeouts but the ERA will likely settle in the 3-3.25 range.
The one change this year (versus past seasons is that he is getting a higher amount of ground balls 52% this year versus 44% career though the corresponding decrease has come in fly balls but not line drives which would have been even more helpful going forward.
It appears he's also adjusted how he's approaching opposing hitters as he's decreased emphasis on his fastball while increasing the amount of cutters, curveballs & changeups that he's throwing.
While his numbers prior to this year indicate he is having a substantial fluke season, I think there is enough in the numbers to indicate that he has turned the corner and is in the middle of a quietly good season.
Seeing that he is one of the few bright spots on what has been another tough season for the Cubs, maybe he doesn't stay with the Cubs and they decide to flip him to a contending team for prospects.
One of the interesting things to note is that if this is indeed his breakout occurring, he would be bucking some historical trends as his most similar pitchers through age 27 listed on baseball-reference are littered with non-household names such as Micah Owings and Blake Stein.
Still, for being drafted in the fifth round of the 2007 draft, Arrieta has done okay for himself as he's tied for third in career WAR amongst players drafted in the fifth round of that years draft (Marlins pitcher Steve Chisek) leading the pack in this area and if he continues the momentum he has had from the first couple of month's this season, he should continue to go up this list.
All numbers, etc, found on either fangraphs.com & baseball-reference.com.