CHICAGO -- Jason Heyward got a fastball he could handle in the eighth inning on Saturday and sent it sailing on a line to deep left-center field. The baseball smacked off the ivy vines and brick wall at Wrigley Field and the Cubs' outfielder hustled into second base for a double.

That kind of hit from Heyward has been a common sight for the North Siders over the first few weeks.

"He's been outstanding," Cubs manager Joe Maddon said this week. "I've not seen this. And I don't even know that I've seen this as an opponent. Right now, the way he's using his hands and the way the ball's coming off hot, his balance, [using] the whole field, power, line drives, everything about his game right now is first rate."

Heyward has been one of the highlights of the young season for the Cubs. Here's a closer look at his impressive start, along with a few more positive and negative developments for the team as it escapes snowy Chicago and heads to Miami this week.

THREE UP

1. Say Hey, Jason

What has been behind Heyward's .375/.460/.700 slash line through a dozen games played? He said it's all about, "not really trying to see the baseball with my eyes." Wait, what? Heyward explained that he meant starting his swing earlier and then reacting to the pitch. In the past, he'd fall into a trap of starting his swing upon seeing the ball. The early results have been an improved launch angle (19 degrees in 2019 vs. 9.0 overall since '15) and exit velocity (92 mph average in '19 vs. 87.7 mph overall since '15). He's pulling the ball less (28.9 percent in '19 vs. 40.8 percent in his career), crushing fastballs (.750 slugging percentage) and chasing less (22.0 percent in '19 vs. 28.5 percent in '18).

2. Changing things up

The changeup has been one of Cole Hamels' main weapons over the course of his career. It's also a pitch on which José Quintana focused a lot of attention during Spring Training. In their past two starts combined, opposing hitters went 0-for-9 with six groundouts, two strikeouts and one lineout against their offspeed offerings. In those Thursday and Friday outings, Quintana and Hamels combined to allow one run on eight hits with 17 strikeouts and one walk in 15 innings. With lefty Jon Lester out, that's the kind of big-game performances the Cubs need out of their rotation right now.

3. Second (base) city

With Javier Baez spending the first month of the season at shortstop, there were questions about what kind of production the Cubs would get out of second base. So far, Chicago has enjoyed a .301/.395/.398 slash line with a 12.6 percent walk rate and .352 wOBA collectively from that position. Veteran utility men Daniel Descalso (.316 average, .813 OPS) and Ben Zobrist (.308 average, .745 OPS), along with David Bote (.269 average, .828 OPS) have each done their part as a piece of Maddon's second-base rotation.

THREE DOWN

1. Walking away

The Cubs' bullpen had a nice week-long shutout streak consisting of 18 2/3 innings, which came to an end in the sixth inning on Saturday. In that frame, Brad Brach and Randy Rosario combined for four walks, including two with the bases loaded. On the day, Chicago's bullpen issued seven free passes (one intentional) to give them an MLB-high 38 walks through 51 innings this year. The team's 15.8-percent walk rate is also the highest mark among big league bullpens. The potential for walks was a red flag coming into the year and it has remained a problem. The Cubs had an 11.0 percent walk rate in '18 (29th in MLB) and have not been below 10 percent since 2015 (8.5 percent).

2. Looking to the stars

The Cubs' offense heads into Sunday ranked second in the National League in average (.272), wOBA (.353) and wRC+ (116), third in on-base percentage (.359) and fourth in slugging percentage (.461), while averaging 6.1 runs per game. So far, it's been Willson Contreras (1.198 OPS), Heyward (1.160 OPS) and Baez (.821 OPS) doing the heavy lifting. Kris Bryant, Anthony Rizzo and Kyle Schwarber have combined for a .205/.315/.378 slash line with one homer per 30.2 plate appearances through Chicago's first 14 games.

3. Catching flak

The small-sample caveat still applies to everything -- good or bad -- at this point in the baseball calendar. That said, one area the Cubs wanted to see improvement in this year was pitch framing. Per Fangraphs, Cubs catchers are currently last in the NL with minus 1.3 Framing Runs. Looking at Statcast, the Cubs also have the highest percentage of ball calls in MLB on pitches around the edges of the strike zone. Contreras' arm has remained a strength (43 percent caught-stealing rate in seven attempts), but he also has three catcher's interference calls against him (something not seen by a Cubs catcher in one season since 1979).