RotoBaller's Nick Mariano looks at some fantasy baseball bats that are entering May extremely hot or cold in the power department.

Welcome back to this investigative piece where we examine players who have seen some notable changes in their power profiles -- for better or for worse -- in 2017. As usual, you don’t need me to tell you that Miguel Sano or Aaron Judge are strong or that Jarrod Dyson and Billy Hamilton are toward the bottom in average exit velocity. It’s been a month and we’ve got

As usual, you don’t need me to tell you that Miguel Sano or Aaron Judge are strong or that Jarrod Dyson and Billy Hamilton are toward the bottom in average exit velocity. It’s been a month and we’ve got some context for recent performances, but do keep a level head on the whole when approaching surges.

I’m out of the office today/tonight (May 4) so everything in this article reflects numbers through May 3. I fully expect some "faller" to go all Anthony Rendon on the world tonight, so place your bets accordingly.

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Power Risers

Marwin Gonzalez - (1B/2B/3B/SS/OF/Everything, HOU):

I suppose we’ve got to lead off with Mr. All-or-Nothing here, as Gonzalez has gone yard five times in his last five games. This comes after a 1-for-27 homerless two-week stretch followed up a 5-for-15 open to the season, with three of those hits being homers. Overall, eight of Gonzalez’s 15 hits have gone for homers. This has resulted in a hilariously tilted 47.1 percent HR/FB rate, bested only by Aaron Judge’s 54.2 percent mark.

Both of them will regress, of course, but at least Judge is a rookie that’s notorious for his power. Gonzalez is in his sixth MLB season and has primarily been in a backup utility role, though he did swat 13 dingers in 518 plate appearances last season for Houston. What’s neat is that his swinging-strike rate is down four percent and his walk rate has nearly tripled to 12.3 percent from last season, so the strong contact is somewhat earned here. Still, he hasn’t suddenly turned into Jon Dowd or anything -- tread carefully and don’t be afraid to cut ties in deeper formats.

Brett Gardner - (OF, NYY):

Brett “The Hitman” Gardner didn’t even have a run batted in on the season prior to April 29 -- when he launched two homers. He then went powerless in his next two games before smashing two more rockets on May 2. Yes, both of these games house his only seven RBI in 2017 as we all know who Gardner is at this point. However, it’s good to note that he’s on a six-game hitting streak now and appears more comfortable in the batter’s box. He had only logged 11 hits over his first 17 games, though he also hasn’t stolen a base since April 10 when he had jumped out to an early MLB-leading five swipes. Streaks are streaks, but do note that Gardner has hit 45 career homers at Yankee Stadium versus just 22 on the road (with 26 more lifetime road ABs) and both of these multi-homer affairs were in the Bronx.

Matt Holliday - (OF, NYY):

Another Bronx Bomber who has enjoyed this little homestand is Holliday, who blasted his 300^th career homer on May 3. The shot was also his third homer and sixth extra-base hit of the past week, which comprises 60 percent of his XBH total despite it only accounting for roughly 20 percent of the season thus far. His 99.9 mph average exit velocity on fly balls and line drives is fifth best in the MLB out of players with at least 50 batted balls this season, giving this writer continued confidence in the veteran slugger.

Michael Conforto - (OF, NYM):

Conforto may not be “surging” in the traditional sense that it’s a huge improvement on what he had been doing before, but his overall batted-ball stats are definitely surging and the power just happens to be part of the package. The oft-mishandled outfielder has been regularly slotted in left field as the Mets’ leadoff hitter and gone 12-for-27 with two doubles, three homers, 10 RBI and a stolen base over his last six games. 11 of his last 20 batted balls have been clocked at 96 mph or greater.

What, you mean a 75 percent HR/FB rate in a six-game sample isn’t sustainable? Don’t worry, we’re keeping our feet on the ground here, especially since he’s just 2-for-9 (.222) with a homer against lefties thus far against a 23-for-61 (.377) and six-homer line against righties. He may never get over that hill entirely, but if he can be platooned effectively by fantasy owners against righties (and not Terry Collins’d) then you’ve got a nice fantasy weapon here.

Kole Calhoun - (OF, LAA):

Calhoun isn’t ever the flashiest name on the board, but he’s been a reliable source of decent pop and an average that won’t kill you over the past three seasons. He’ll rarely make you jump for joy, but he also isn’t supposed to go 6-for-44 with zero extra-base hits -- as he did across the two weeks prior to this one.

He’s made up for it by hitting homers in his last three games and an overall 12-for-34 run over his last seven contests. He’s only struck three balls with a negative-degree launch angle over that span and just looks to have regained his confidence out there.

Power Fallers

Mookie Betts - (OF, BOS):

Betts has posted average exit velocities of 91.1 and 90.6 mph over his last two seasons, but has opened '17 with an 88.6 mph AEV thus far despite some recent valiant efforts. He’s drilled 14 balls at 90 mph or more in the past week, but five of them have been at negative angles with only one of them getting through the infield for a single. Out of the other nine, only three have resulted in hits (two doubles, one single). The overall read here, for me, is that he’s hitting the ball pretty well and should see the results improve in short order. He’s a nice buy low if his fantasy owners are getting impatient.

Maikel Franco - (3B, PHI):

Franco has gone 7-for-25 -- six singles and a double -- over his last week of play, but this more about the fact that he’s still doing well even if the power isn’t quite translating. He’s only smacked two balls that registered as “soft contact” over the past week according to Fangraphs. That said, his .222 average and .220 BABIP have owners a little alarmed despite the 23 RBI thus far, which is good since RBI aren’t predictive in any way. He’s hitting the ball just fine and is showing improved zone-discipline metrics, so this is a “hold”.

Gregory Polanco - (OF, PIT):

Yeah, this is a serious issue at this point. It’s been a month and Polanco only has a homerless four RBI to show for it. He’s still being religiously penciled in as Pittsburgh’s cleanup hitter, but how long will they tolerate a .229/.319/.313 slash line out of that spot? He has one measly barrel thus far and his 86.6 mph AEV is way below his usual 90.5 mph mark (90.7 in ’16, 90.4 in ’15).

What’s most interesting is that pitchers seem to be picking on the fact that he can’t hit a slider to save his life. He hit .146 against them last season (13 hits and 48 whiffs on 387 pitches seen) and has only tallied one hit off of the 71 sliders he’s seen thus far in 2017 alongside an embarrassing 15 whiffs already. Fangraphs says pitchers have upped his slider diet to 20.8 percent from 14.5 percent last season, which combined with a potential shoulder issue, could really be exposing him.

Chris Davis - (1B, BAL):

It’s no secret that Chris Davis is battling at the dish right now, but the problem is that he’s battling as if Genghis Khan is pitching to him. He’s gone 8-for-56 with 25 strikeouts and just two doubles against the Mongolball, as it’s a combination of the quality of contact and making contact in the first place. His 16 percent swinging-strike rate is ugly, but his fly-ball rate is also down a shade over 10 percent from last season. While it’s translating to more line drives per Fangraphs, they just aren’t as potent when you consider his 87.3 mph AEV is down nearly five ticks from his 92 mph AEV from ’16. He’s a streaky guy so you can hold until he rights the ship, but this is a legitimate slump.

Jackie Bradley Jr. - (OF, BOS):

I debated talking about Hunter Renfroe or Carlos Gonzalez here, but I feel like JBJ deserves some context. I was one of the louder trumpets this offseason about Bradley’s high price point in drafts given his streaky nature and short track record, but 2017 has been pretty rude to him (on top of some legitimate struggles). His last seven games have seen him go 2-for-24 with zero XBH and eight strikeouts, so let’s see what’s going on here.

He’s sporting an ugly 85.7 mph AEV despite an aesthetically-pleasing 40.5 percent hard-hit rate on the season per Fangraphs, but it’s always important to check the actual Statcast data behind the FG data. Interestingly enough, Baseball Savant lists JBJ with six balls hit at >94 mph, but only one (a 101.6 mph grounder) turned into a hit as the others had rather poor angles. His overall swinging-strike rate is up at 13.7 percent (10.8 percent in ’16) and is 16.2 percent in the past week. When you’re whiffing at a higher clip than Chris Davis then you better be destroying the ball when you connect. He’s not. I’m worried. He’s better than this and should rebound a bit, but he’s highly unlikely to make good on being drafted as the OF33 this season.

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