A look at some popular pick-ups. All numbers referenced were found on fangraphs.com and ownership percentage numbers referenced found on Yahoo! Fantasy
Currently owned in 28% of leagues. The last few days have been very good to Navarro as he has homered in his last two games and has an OPS north of 1.000 in his last five games.
Is this a sign of things to come or has he reached a rare peak. So far, his batting average is at .283 but his BABIP of .302 is well above his career total of .278 and he has gotten moderately lucky on his HR/FB rate which is 9.4% compared to 7.8% for his career. He is also approaching his career high for plate appearances which was 470 for the 2008 Rays.
Over 470 plate appearances, and adjusting for his normal numbers, I think he would have a line of:
.262/.336/.383 10 HR 59 RBI 35 R 2 SB
Bottom line is that you may get a decent batting average and possibly double-digit home runs but I don't think he'll be close to the top flight option that he's been playing like over the last week.
Currently owned in 40% of leagues and getting close to playing himself off the list (the minimum is 50% ownership). He has provided a spark to the Twins lineup since being called up but can he keep this up. The main red flags are that his BABIP (.389) and HR/FB rate (18.2%) indicate that he may be playing over his head and his low walk rate (2.8%) indicate that his success may be short-lived. His projection is for 520 plate appearances (his career high from 2013 high A+ ball).
.247/.275/.444 12 HR 87 RBI 53 R
The main thing keeping his projected numbers down are that it's too early to tell if his 18.2% HR/FB rate is indicative of his actual abilities. For players with less than 1,000 plate appearances, i'll typically assume a 10% HR/FB rate baseline. Also, if he becomes more patient at the plate and his walk rates move closer to his minor league totals, this would lead to a much more optimistic outlook.
Currently owned in 14% of leagues. He has hit for limited power so far but a recent hot streak has moved his batting average to .318. The main question is whether he can keep this up as he does have a relatively high BABIP (.354). His projection is for 605 plate appearances (his career high in the minors for 2012):
.269/.341/.347 12 HR 40 RBI 61 R
I think he'll be a reasonably valuable player for the Giants as I think he'll do just enough on offense to justify playing him (so far his defense appears to be solid). The question is whether the power will develop. It could very possibly turn out that even double-digit home run power may be overly optimistic. Again, this is based on small sample size as he currently sports a low HR/FB rate of 2.6% but I attempted to work towards 10% with the absence of further data.
Currently owned in 22% of leagues and had the benefit of mashing against a Brewers team that seems determined to self-destruct. Currently, he is at his career high of 462 plate appearances so I am going to factor this into the below projection.
.228/.328/.374 12 HR 44 RBI 51 R
While the other players listed up have at least a debatable level of value, I think Valbuena has reached his peak performance which even then has some flaws. Despite a .248 batting average this is above his estimated actual ability as his BABIP (.290) is higher than his career total. He has over-acheived in the home run department and I think he's more of a low double-digit player. The one good thing going for him is that he is at least patient at the plate.
Currently owned in 29% of leagues. Betts has played relatively well since being called up by the Red Sox. The question is what to expect going forward. My projection (based on 551 plate appearances..which he got in the minors last year is:
.284/.374/.466 17 HR 52 RBI 71 R 20 SB
Going into 2015, Betts is going to be a good bet (pun not intended). Nothing in his numbers indicates that he's playing over his head (.288 BABIP/11.4% HR/FB Rate), he's shown that he's not going to swing at everything (9% BB Rate) and he's shown that he can hit for a reasonable amount of power and steal double digit bases. Depending on playing time and how the wind blows, he could easily be a 20/20 player next year.
Currently owned in 8% of leagues but has himself a nice little 4 game hit streak. His projection is based off his career high in plate appearances (421) from last year.
.245/.290/.353 9 HR 39 RBI 39 R 9 SB
This is not meant to devalue what Lagares contributes to the Mets with his defense (he has been 4 wins above replacement despite having a wRC+ of 102). For fantasy players, I don't think he's going to help all that much
While I think there's the potential of him hitting a few more home runs, his BABIP is running a little high and I think he's closer to a .245 hitter. Ad in low walk rate, modest home run/stolen bases totals he appears headed to being an elite defensive player (but not so much on offense.