The 2018 WTA Season is in the books. Now to synthesize what just happened over the last 11 months.

WTA Insider breaks down the season's serving statistics, which saw Julia Goerges and Ashleigh Barty separate themselves from the pack. While Naomi Osaka showed impressive improvements in her service game, Karolina Pliskova, Maria Sharapova, and Venus Williams found holding their serves to be a much tougher task this season.

2018 was a banner season for 30-year-old Julia Goerges. After a big 2017 saw her win titles for the first time since 2011 and finish just outside the Top 10, this season was about breaking barriers. Not only did Goerges successfully consolidate her season, winning titles in Auckland, Luxembourg, and a final in Charleston, but the German also broke through to make her 1st Slam semifinal at Wimbledon. 

And you can't make a Wimbledon semifinal without having an effective serve. En route to another strong season, No.14 Goerges fired a tour-leading 493 aces over 68 matches, outpacing the field by nearly 100 aces, and ending Karolina Pliskova's three-year reign as the season-ending ace-leader. 

Goerges' 400+ tally puts her in an exclusive club of players who have hit 400 or aces in a season, a club that includes on Serena Williams and Karolina Pliskova. 

Goerges was most dangerous behind her first serve. She led the tour in 1st serve points won this season:

First Serve Points Won in 2018: 

1. Julia Goerges: 73.8% (68 matches)
2. Ashleigh Barty: 71.6% (61 matches)
3. Kristyna Pliskova: 71.2% (36 matches)
4. Naomi Osaka: 70.1% (60 matches)
5. Madison Keys: 70% (42 matches)

While Goerges led in total aces, Kristyna Pliskova led in ace efficiency. The Czech lefty hit 276 aces in just 36 matches, a tour-leading average of 7.7 aces per match.

When it comes to pure serving success, it was a neck-and-neck battle all season between Ashleigh Barty and Goerges for the top two spots, with the young Aussie overtaking the German with her title-winning performance at the WTA Elite Trophy Zhuhai, finishing the season at 78.7% of her service games this season. 

While Barty posts great numbers behind her first serve - she is second only to Goerges (see above) - the Aussie tops the field when it comes he winning percentage behind the second serve. Two women were able to break the 50% mark this season: Barty and Caroline Garcia. 

Second Serve Points Won in 2018:

1. Ashleigh Barty: 52.2% (61 matches)
2. Caroline Garcia: 51.3% (61 matches)
3. Sloane Stephens: 49.15% (54 matches)
4. Elina Svitolina: 49% (59 matches)
5. Petra Martic: 48.9% (43 matches)

One new name that now features more prominently in the Top 5 serving numbers: US Open and Indian Wells champion Naomi Osaka. The 21-year-old's dangerous serve evolved into a more consistent weapon this season. Amongst the Top 50, Osaka had the third-best rate of improvement in service games won compared to last season:

1. Hsieh Su-Wei (TPE)
2017: 53.3%
2018: 65.2%
Improvement: 11.9%

T-2. Elise Mertens (BEL)
2017: 62%
2018: 69.3%
Improvement: +7.3%

T-2. Ajla Tomljanovic (AUS)
2017: 55.9%
2018: 63.2%
Improvement: +7.3%

3. Naomi Osaka (JPN)
2017: 69.6%
2018: 76%
Improvement: +6.4%

In contrast to Osaka's improvements, three veterans saw their service numbers take a notable dip in 2018. No.8 Karolina Pliskova, No.29 Maria Sharapova, and No.40 Venus Williams all saw their percentage of service games won drop more than 5% in 2018, with Pliskova and Venus also experiencing a rankings drop from 2017. 

1. Daria Gavrilova (AUS)
2017: 66.1%
2018: 58.8%
Decline: -7.3%

2. Anett Kontaveit (EST)
2017: 73.8%
2018: 66.9%
Decline: -6.9%

3. Maria Sharapova (RUS)
2017: 73.5%
2018: 67.4%
Decline: -6.1%

4. Alison Van Uytvanck (BEL)
2017: 76.5%
2018: 70.9%
Decline: -5.6

5. Karolina Pliskova (CZE)
2017: 79.1%
2018: 73.6%
Decline: -5.5%

6. Venus Williams (USA)
2017: 71.4%
2018: 66.1%
Decline: -5.3%

Stats and Information provided by SAP Analytics.