Danny Duffy had a breakout season in 2014. He delivered an excellent 2.53 ERA and 1.11 WHIP in 150 innings, helping to lead the Royals to their first playoff berth since the George Brett era. Duffy is only 25 years old and many people are predicting even better days ahead for the young hurler. But there are a lot of big red flags in his peripheral numbers that indicate he is in store for a major downfall.
Duffy finished as a top 40 starting pitcher in fantasy leagues this year despite not joining the Kansas City rotation until May. Depending on your league's scoring system Duffy's final overall rank was likely in the 120-130 range among all players. He is likely to be drafted in the 10th - 12th round in fantasy leagues next March, maybe even before that if someone in your league believes in his "breakout" 2014 season. That is way too soon to draft Duffy. I strongly advise you to let someone else take him and I will tell you why.
Duffy's rank among the 112 pitchers who threw 140+ innings this season:
2.53 ERA 11th
1.11 WHIP 19th
.239 BABIP 3rd
6.81 K/9 76th
3.19 BB/9 88th
2.13 K/BB 95th
9.9% K%-BB% 89th
3.83 FIP 61st
4.42 xFIP 103rd
4.31 SIERA 96th
We can see that the first three statistics do not match the rest. Duffy's ERA and WHIP both look a LOT better than his peripherals. His 2.53 ERA is almost two full runs better than his xFIP and SIERA. That is not a good thing because xFIP and SIERA are very good at predicting the future. That means Duffy's ERA is likely to be over 4.00 next year.
Duffy has benefited very much from a flukishly low BABIP that is not backed up by his batted ball rates, which indicate his BABIP should have been at the league average of .295 for the season. The odds are not good that Duffy will get so lucky on BABIP next season. Expect him to allow a lot more hits per inning, which will do a lot of damage to his WHIP and ERA.
Strikeouts have been a problem for Duffy as well. He simply doesn't strike out nearly enough batters to maintain such a good ERA. His strikeout to walk ratio is worse than league average, leading to a very poor 9.9% K%-BB% that is well below the 12.7% league average. Pitchers who have below average K%-BB% scores are not able to remain good pitchers for long. This is especially true in fantasy baseball, because Strikeouts are one of the scoring categories. In real baseball teams are only concerned with how many runs a pitcher gives up, but in fantasy we care about silly things like Ks and Wins in addition to ERA and WHIP.
Given that Duffy has done such a poor job in terms of striking out batters it is no surprise that he ranks near the bottom of the league in xFIP and SIERA. Based on these peripheral stats we can expect a steep dropoff in Duffy's fantasy stats next season. I would not advise taking Duffy before the 20th round of a 12-team draft. You won't have the option of taking him that late in a draft because somebody else will draft him long before that. Let somebody else have him. You will be glad you did. You will get a good player with your 10th round pick while the guy who drafts Duffy will get a rude surprise when he poops the bed next season.
If you do end up snagging Duffy in the draft or if you already have him in a keeper or dynasty league, I would suggest dealing him while his trade value is high. That shiny 2.53 ERA and all the attention the Royals are getting in the playoffs this year combine to make his trade value right now higher than it will ever be again in the future. Now is the time to shop him around to see what you can get. I bet you can obtain a much more proven and reliable player via trade.