Hendricks has just been straight up killing it for months now. I wanted to take an objective look at Kyle Hendrick's Cy Young chances. The NL ERA leaders can be found here. I have added Hendrick's and Bumgarner's performances in from today.

Player|IP|ER
:--|:--
Kershaw|1.79|121.0|24
Hendricks|2.17|133.0|32 Bumgarner|2.20|163.7|40 deGrom|2.41|119.7|32 Arrieta|2.59|142.3|41 Syndergaard|2.64|129.3|38 Cueto|2.73|155.0|47 Strasburg|2.80|138.3|43

So immediately, you see that Kershaw is way ahead in ERA. It's astounding that with all the time missed, he's only pitched 12 innings less than Kyle. If he can get back and get up in time to make ~6 more starts for ~40-45 IP, he will be very deserving.

Assuming Kershaw misses too much time and is out of the discussion, it's looking like a two man race between Hendricks and Bumgarner. Hendricks has a ever-so-slight ERA edge, right now, but Bumgarner is a Lackeyhorse and has a massive edge in IP.

How much is the difference between Hendricks and Bumgarner? In the table below, I show the difference in IP and ER between them. For comparison, I've included Strop's numbers as well.

Player|IP|ER
:--|:--
Bumgarner|2.20|163.7|40 Hendricks|2.17|133.0|32 Bum\Hendricks|2.35|30.7|8 Strop|2.76|42.3|13

What you see is that in addition to providing Hendricks' production, Bumgarner has also given better than Strop production for 75% of his innings. Getting all of those extra outs at that effective of a clip is definitely very valuable. I'd say that Kyle needs to aggressively close the gap in IP (which'll be tough given (a) our loaded bullpen situation (b) Bumgarner is still pitching very long outings and (c) the season's 2/3 over), or pull ahead in ERA by at least 0.1-0.2 points to firmly swing the chances in his favor.