It seems that Konta's game is not very appreciated in this thread. To me, it is irrelevant whether a shot looks good or not, technically every safe variation of the technique has its advantages and disavantages. (by safe I mean that it is natural to the body and will not lead to injuries).
Take Kerber's abbreviated forehand motion. She is not a natural leftie, but one could argue that this abbreviated forehand is what helped her win Wimbledon and why she is such an effective counterpuncher (who can consistently beat Serena). The reason for this is that it allows her to rebalance herself and get ready for the next rally very quickly, which is important for fast surfaces.
I do not know much about Konta's game, but she is a very talented player and probably the most qualified quarterfinalist to take on Serena
(too bad this will not happen this tournament). Personally, when her forehand is on, it looks more scary than many other players' serves
Actually you make an interesting point about Kerber. Kerber for sure does not have natural looking strokes, especially on the forehand side. Her serve has always been a liability, particularly her second serve. However, her leftiness is an advantage, like Nadal she is someone who writes right handed but plays left handed. But in cricket that's quite normal where a player might bowl left handed and bat right handed, or bowl right handed and bat left handed.
But what marks Kerber out is her tremendous athleticism, I've been fortunate to watch her play on two different surfaces in England and France on a few occasions, she is very quick, I imagine she has fast twitch fibres. For a player around the height of 5 ft 8 inches (1 metre 70?), her smashing technique is absolutely superb, she hardly ever misses, which means she has good positioning skills often.
In Kerber's case her speed around the court, allied with the ability to play big points well at the big moments has allowed her to win three slams and play in many other finals (she's lost quite a few over the years). I saw her win her first title in Paris Indoors in 2012 but then saw her lose the 2012 and 2014 Eastbourne finals. To play the big points well you have to be mentally calm at the right moments, like going up to take a penalty in a shoot out.
Unfortunately for Konta, it is the lack of calm which is really holding her back, I can't decide which comes first. Is it her lack of sound technique which gets exposed when the pressure is on, hence those wild errors in the mid court at important moments in matches over a period of many years? Or is it her lack of calm, she gets flustered and can't think coherently, leading to those wild errors over and over again? Maybe that's why I said it is like watching a computer malfunction. It is just very strange to watch, especially the French Open semifinal. After all, she is an experienced player and she had all the support in the crowd and those wtaching at home, myself included, hopefully that would have been an inspiration as opposed to being a hindrance.