At this level small to moderate differences can be big though.
Caro's forehand is probably the next biggest thing in terms of technique for her to work on. We saw an improved forehand sometimes towards the end of the year but it needs to show up consistently.
With regard to THIS stat,I suspect that you're overrating its significance.
According to your graphic,the players with a better percentage are usually around 65 or 66% of FIRST serve points won,while Caro is just above 63.If you had 100 service points in one match--and it's quite uncommon to have a match THAT long,then there would only be a difference of 2 or 3 points per match.In a match of typical length,we'd be talking only 1 or 2 points,and that is HARDLY an impactful difference by itself.Caroline could EASILY offset those couple lost points by losing fewer points than her opponent due to defensive skills
I'm NOT saying that your stat is meaningless,but it requires a broader perspective before it can carry too much weight.For example, if a certain player wins 70% of her 1st serves instead of Caroline's 63...yet only connects on 48% of her first serves...and wins about 20% of her 2nd-serve points...then her "edge" on Caro is pretty worthless.To ME,the bigger issues are whether or not Caroline can win easy points off her serve to reduce wear-and-tear,NOT merely win the point...and the other question is whether or not Caroline's SECOND serve is strong enough so as not to leave her helpless vs. tough ROSers.Obviously,a player with a feeble second serve will often feel more nervous on her FIRST serve on crucial points...knowing that she MUST get it in or else be doomed on the 2nd-serve follow-up.
Stats can be effective tools,Protoss,but they're usually not all-telling;I remember last year when some NFL geeks blabbed about how no 9-7 team had ever won the SB...and back in 2005 when some of the same numbers-only nerds prattled about how no #6 seed had ever won the SB...as if those details would destroy the Giants' and Steelers' respective confidence and prevent them from winning
...a basic grasp of the sport would've told any fan that injuries during the regular season kept both of those championship squads from finishing with the W/L record that they probably would've gotten otherwise
I can see that your sig focuses on Star Wars and not Star TREK,but I'll take you back to ST film #6 when Spock,forgive my paraphrase,told his young Vulcan disciple that logic was only the BEGINNING of reasoning....I would argue that it was the same with stats analysis in re understanding a sport