I've read about decoupling, but I can be kind of dense and I don't really get it completely. My numbers can be all over the place, is it really showing me anything about my fitness or is it just noise?

Edit: here was some data for a climb today...

Climb:

Duration: 17:25

Work: 271 kJ

TSS: 25.5 (intensity factor 0.938)

Norm Power: 263

VI: 1.01

Pw:HR: 4.8%

Pa:HR: 15.7%

Distance: 2.924 mi

Elevation Gain: 1232 ft

Elevation Loss: 30 ft

Grade: 7.8 % (1203 ft)

MinMaxAvg

Power: 0 456 259 watts

Heart Rate: 119 185 173 bpm

Cadence: 55 109 81 rpm

Speed: 2.3 18.7 10.1 mph

Pace 3:12 26:06 5:57 min/mi

Altitude: 196 1398 798 ft

Crank Torque: 0 584 278 lb-in

Some SST yesterday

Entire workout (229 watts):Duration: 1:12:02 (1:17:18)

Work: 992 kJ

TSS: 90.6 (intensity factor 0.869)

Norm Power: 243

VI: 1.06

Pw:HR: 6.9%

Pa:HR: -27.48%

Distance: 24.311 mi

Elevation Gain: 2076 ft

Elevation Loss: 2077 ft

Grade: -0.0 % (-1 ft)

MinMaxAvgPower: 0 613 230 watts

Heart Rate: 55 173 159 bpm

Cadence: 2 124 94 rpm

Speed: 0 52.3 20.3 mph

Pace 1:09 0:00 2:57 min/mi

Altitude: -14 804 299 ft

Crank Torque: 0 852 208 lb-in

And a group ride yesterday

Entire workout (229 watts):Duration: 54:33 (1:01:23)

Work: 751 kJ

TSS: 78 (intensity factor 0.926)

Norm Power: 259

VI: 1.13

Pw:HR: 12.58%

Pa:HR: 5.12%

Distance: 20.533 mi

Elevation Gain: 1287 ft

Elevation Loss: 1297 ft

Grade: -0.0 % (-10 ft)

MinMaxAvgPower: 0 716 230 watts

Heart Rate: 67 185 163 bpm

Cadence: 1 121 91 rpm

Speed: 0.7 50.8 22.7 mph

Pace 1:11 87:47 2:39 min/mi

Altitude: 47 250 115 ft

Crank Torque: 0 785 213 lb-in